Pathology Education Instructional Resource - User contributions [en]

Main Page

2014-07-29T21:21:30Z

Seung Park:

<div id="mf-home">
Welcome to the Pathology Education Instructional Resource (PEIR), a web teaching resource and informatics training grounds directed by [https://services.medicine.uab.edu/facultyDirectory/FacultyData.asp?s_lname=Park&s_keyword=&s_fname=Seung&FacultyTypeID=&s_Department_Name=&s_ResearchTitle=&FID=61255 Seung Park, MD] and [https://services.medicine.uab.edu/facultyDirectory/FacultyData.asp?Entity=JHS&vwAllfacultyPage=1&FID=19493 Peter Anderson, DVM, PhD]. Please contact one of us directly if you have any interest in contributing and/or editing content.

== PEIR Projects ==
=== Image Libraries ===
* The [{{SERVER}}/library PEIR Digital Library] contains more than 30,000 curated teaching images, and is our flagship project.
* [http://peir-vm.path.uab.edu/ PEIR-VM] is a compehensive teaching repository of whole slide images.

=== Teaching ===
* [[IPLab]] is a comprehensive online course in classic pathology.
* [[Histologic]] is a comprehensive histology manual.
* [[Cytologically Yours]] is an online cytopathology teaching resource for pathology residents and fellows.
* [[This Is Your Brain On Informatics]] consists of the class notes for GBSC703-01D/STP2146: "this is your brain, THIS IS YOUR BRAIN ON INFORMATICS".

__NOGLOSSARY__

Histologic:Chapter 1

2014-07-29T15:11:48Z

Seung Park:

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 11+
* [http://www.mozilla.org/ Mozilla Firefox] 9+
* [http://chrome.google.com/ Google Chrome] 17+
* [http://www.opera.com/ Opera] 17+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

__NOGLOSSARY__

Histologic:Chapter 1

2014-07-29T15:11:22Z

Seung Park: /* Using Histologic */

Histologic:Chapter 1

2014-07-29T15:09:21Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 11+
* [http://www.mozilla.org/ Mozilla Firefox] 9+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-29T15:08:03Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 11+
* [http://www.mozilla.org/ Mozilla Firefox] 4+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-29T15:03:17Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 9+
** Fullscreen mode for whole slide images is not yet supported in IE, but will be as of version 12
* [http://www.mozilla.org/ Mozilla Firefox] 4+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-29T15:02:38Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 9+
** Fullscreen mode for whole slide images is not yet supported
* [http://www.mozilla.org/ Mozilla Firefox] 4+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-29T02:32:42Z

Seung Park: /* Whole Slide Imaging Example */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 9+
* [http://www.mozilla.org/ Mozilla Firefox] 4+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00284</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-29T02:14:44Z

Seung Park:

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

[[Histologic]] is optimized and tested for modern web browsers, including:

* [http://windows.microsoft.com/en-us/internet-explorer/download-ie Microsoft Internet Explorer] 9+
* [http://www.mozilla.org/ Mozilla Firefox] 4+
* [http://chrome.google.com/ Google Chrome] 10+
* [http://www.opera.com/ Opera] 12+

Older browsers may work, but are not explicitly supported.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00002</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 8

2014-07-28T23:54:43Z

Seung Park:

== Introduction ==

One component of the immune system is lymphatic tissue which consists of reticular connective tissue infiltrated with lymphocytes. This tissue occurs in many regions of the body as diffuse, dense or nodular collections of lymphocytes or as lymphatic organs in which the lymphatic tissue is surrounded by a definite capsule or an epithelium. Lymphatic organs include lymph nodes, thymus, spleen and tonsils.

== Lymph Nodes ==
[[File:HistologicChapter8LymphNode.png|thumb|200px|Lymph Node]]
Lymph nodes are round, ovoid or bean-shaped organs found widely distributed in the body. Important groups of lymph nodes occur in chains along the course of blood vessels in such regions as the axilla, groin and mesentery. Lymph nodes are the only lymphatic organs to have an afferent lymphatic supply. They are interposed in the lymphatic drainage of numerous regions of the body. The lymph flowing through the nodes is filtered and phagocytic activity occurs on the particulate matter carried in the lymph. Lymph nodes are important centers for the production of lymphocytes, plasma cells and antibodies. Lymphocytes and antibodies are added to the lymph, which leaves the node by way of the efferent lymph vessels. Lymph nodes are fixed to surrounding connective tissue by loosely arranged fibers that continue into the capsule of the node.

=== Slide 63: Lymph Node, and Slide 35: Mesenteric Lymph Nodes (H&E) ===

Scan these sections with low power to observe the large number of small darkly staining cells. Most of these cells are lymphocytes. On slide 35, study the largest node first.

Identify the capsule of rather dense irregular connective tissue surrounding the lymphatic tissue. Outside the capsule may be seen loose connective tissue containing blood vessels, lymphatic vessels, fat and an occasional nerve.

One of the nodes has an indentation on one side, this is likely the hilus where blood vessels and nerves enter and leave the node, and where the efferent lymphatic vessels exit.

Observe the rounded concentrations of lymphocytes, the lymphatic nodules (primary nodules), in the outer regions (the cortex) of the node. Some of the nodules may have a light central area, the germinal center, indicating that the nodule was active at the time of fixation.

Continue the study of slides 63 and 35 with the medium and high power.

Observe the cortex. The lymphatic nodules and cords of dense lymphatic tissue radiating toward the center of the node are located in the cortex. The cords of dense lymphatic tissue break up into anastomosing medullary cords. The reticular connective tissue framework of the node is obscured by these dense accumulations of lymphocytes.

Look for the medulla in the lymph nodes. This is an inner zone radiating from the hilus. No sharp boundary occurs between the cortex and the medulla, but lymphatic nodules rarely occur in the medulla. Medullary cords of dense lymphatic tissue extend from the lymphatic nodules of the cortex into the medulla. The cords branch and anastomose with each other and are surrounded by the medullary sinuses. The areas between the medullary cords are the medullary sinuses. The sinuses contain reticular cells, reticular fibers, and scattered lymphocytes. The reticular cells are fibroblast-like and electron micrographs show their processes completely enclosing (surrounding) the reticular fibers which they produce.

Identify afferent lymph vessels in the capsule and look for an afferent lymph vessel piercing the capsule to enter the subcapsular sinus. Several of these vessels penetrate the capsule at an angle to bring lymph to the node. These thin-walled, endothelial-lined tubes contain valves and their walls possess very little connective tissue. Afferent lymph vessels are absent at the hilus. Look for efferent lymph vessels in the hilus or near the nodes (slide 35).

Observe the sinuses of a lymph node and attempt to visualize the pathways by which lymph enters, flows through, and leaves a lymph node.

*Identify the subcapsular sinus (marginal sinus) which lies just beneath the capsule and receives lymph from the afferent lymphatics. According to recent reports both macrophages and endothelial cells line the sinuses. Reticular cells can be identified in this comparatively open area.

*The trabecular sinuses, similar in structure to the subcapsular sinus, lie adjacent to the trabecular. These are sometimes called intermediate or cortical sinuses. These areas of diffuse lymphatic tissue allow lymph to flow into the medullary sinuses.

*The anastomosing medullary sinuses occur in the central portion of the lymph node. These are areas of loose lymphatic tissue which lie between the medullary cords and the trabeculae.

*All of the sinuses may contain macrophages that engulf particulate debris and degenerating cells in the lymph. Identify macrophages on slide 63. There are very few on slide 35.

*Efferent lymph vessels collect the lymph from the medullary sinuses.

==== Slide 63: Lymph Node ====
<peir-vm>UAB-Histology-00063</peir-vm>

==== Slide 35: Mesenteric Lymph Nodes (H&E) ====
<peir-vm>UAB-Histology-00035</peir-vm>

=== Slide 93: Lymph node (H&E) ===

Slide 93, Lymph node (H&E) in the hilus of the lung. These nodes help filter dust, carbon particles, and other debris that get into the lungs.

Note the innumerable macrophages filled with dark, particulate matter. Some of the dark particles may not have been ingested by macrophages or may be deposited after ingestion and rupture of the macrophage.

The node has so many active macrophages that the lymphatic tissue has been greatly reduced. Note the small cortex and only scattered medullary cords, if any.

Lymph Node Details. Since you are now familiar with the general structure of lymph nodes, study the nodes on Slides 35 and 63 in greater detail.

<peir-vm>UAB-Histology-00093</peir-vm>

==== Slide 35: Mesenteric Lymph Nodes (H&E) ====

In slide 35 note that most of the lymphatic nodules contain germinal centers containing small and medium-sized lymphocytes, macrophages, and lymphoblasts (few in number).

Small and medium-sized lymphocytes as well as macrophages are more prominent in the germinal centers than are lymphoblasts. The medium-sized lymphocytes have more euchromatin than small lymphocytes, the nucleolus is larger, and the cytoplasm is more basophilic. The macrophages may have an acidophilic, vacuolated cytoplasm and an eccentrically located nucleus.

<peir-vm>UAB-Histology-00035</peir-vm>

==== Slide 63: Lymph Node ====

Lymphoblasts (large lymphocytes) are more easily recognized on slide 63, although fewer germinal centers are present on this slide. To identify lymphoblasts, look in the germinal centers for relatively large cells that have basophilic cytoplasm (not very distinct on our slides) and a large mostly euchromatic nucleus with one or two prominent nucleoli.

The germinal centers have a stroma of reticular fibers and reticular cells. Those cells, which have long almost dendritic-like protoplasmic processes, are called dendritic cells. They trap antigens in the presence of antibodies. Dendritic cells are difficult to identify so do not try to find them. Rather, identify the more typical reticular cells in the subcapsular and medullary sinuses on slide 63. Numerous macrophages can also be found in these sinuses.

Observe on your slides that the germinal centers are accentuated by a number of densely packed small lymphocytes that form a ring around the centers. Note that germinal centers are not usually present before birth, nor are they present in animals raised in a germ-free environment.

<peir-vm>UAB-Histology-00063</peir-vm>

== Thymus ==
[[File:HistologicChapter8Thymus.jpg|thumb|200px|Thymus]]
The thymus is unlike other lymphatic organs in two major respects: (1) its stroma consists of a framework of connecting epithelial reticular cells (cytoreticular cells) derived from endoderm. This stroma is not typical reticular connective tissue that is derived from mesoderm and characteristic of other lymphatic organs. (2) Lymphatic nodules are lacking, but the organization of the lobules into a cortex and a medulla may give the unwary student the impression that nodules are present.

Four slides of thymic tissue are to be studied. Slides 55 and 61 are from young individuals. Slide 60 is from a nineteen-year-old, and slide 59 is an involuted thymus from a fifty-year-old person. Since the thymus responds to illness by undergoing stress involution, it should be realized that some sections might not be optimal for studying all features. Slide 55 from a ten-day old child best shows the normal features for a young thymus.

=== Slide 55: Thymus (Infant) (H&E) ===

Observe the thin connective tissue capsule surrounding this organ and the septa (trabeculae) which project inward from the capsule. These strands of connective tissue subdivide the thymus into lobules. Blood vessels are contained within some of the larger septa.

Note that most lobules consist of a darkly stained cortex and a lighter-stained medulla. Reconstructions of the thymus show that the medulla is continuous from one lobule to the next lobule within the same lobe. The palely stained medulla should not be confused with germinal centers of lymphatic nodules. The thymus lacks lymphatic nodules. The medulla stains lighter than the cortex because it contains more epithelial reticular cells and fewer lymphocytes than are contained within the cortex. The epithelial reticular cells are similar in appearance to primitive reticular cells of other lymphatic organs. Identify these in both cortex and medulla.

Identify the acidophilic-staining thymic corpuscles (Hassall’s corpuscles) in the medulla. These structures, unique to the thymus, consist of concentrically arranged epithelial reticular cells. Some of the cells in the center are degenerating. In this young thymus, the thymic corpuscles are small. Note that many are considerably larger on slide 60 and on slide 59.

Note there are no lymphatic sinuses in the thymus but numerous small blood vessels course through the organ. They are located mainly in the septa and the medulla.

In the cortex are some small, rounded clear areas about the size of a large cell.
These areas may contain palely stained macrophages, some of which have been active in engulfing other cells.

Study the section under high power. Distinguish between lymphocytes and epithelial reticular cells. Examine the thymic corpuscles closely. Study the macrophages.

<peir-vm>UAB-Histology-00055</peir-vm>

=== Slide 61: Thymus (H&E) ===

Slide 61, Thymus, (H&E) is from a seven-year-old child. Identify as many features as possible. Observe how different this thymus appears from the section of the younger thymus previously studied on Slide 55. Slightly more connective tissue and fat are present in the seven-year-old thymus and the thymic corpuscles are larger.

<peir-vm>UAB-Histology-00061</peir-vm>

=== Slide 60: Thymus (H&E) ===

Study slide 60, Thymus (H&E) from a nineteen-year-old. Note the reduced number of lobules that are widely separated by a large increase in the amount of fat. Identify the thymic corpuscles. Observe that arterioles, venules, and larger blood vessels are absent from the cortex of the lobules. The thick-walled capillaries that form the blood-thymus barrier are not readily identifiable on our slides.

<peir-vm>UAB-Histology-00060</peir-vm>

=== Slide 59: Thymus (H&E) ===

Study slide 59, Thymus (H&E) from a fifty-year-old individual. Compare this involuted thymus with the sections of thymus previously studied.

<peir-vm>UAB-Histology-00059</peir-vm>

== Tonsils ==

Tonsils are defined as aggregates of lymphatic nodules associated with an epithelium. The palatine tonsils, pharyngeal tonsil and lingual tonsils form a ring of lymphatic tissue around the entrance to the throat (pharynx). This protective tonsillar ring is at the oropharyngeal isthmus. The “intestinal tonsils”, better known as aggregated nodules (Peyer’s patches) are located in the ileum of the small intestine.

=== Palatine Tonsil ===

==== Slide 52: Palatine Tonsil (H&E) ====

Observe that “one side,” the surface, is covered by stratified squamous epithelium. From the surface a total of 10 to 20 deeply invaginated epithelial pockets called crypts extend into the substance of the organ. Note that the epithelium lining the crypts is continuous with the surface epithelium. Only a few crypts will be present on any one slide.

On the side of the tonsil opposite the surface epithelium will be found a capsule of dense irregular connective tissue that serves to attach the organ to the wall of the oropharynx. Identify the capsule and the connective tissue septa that extend from it to partially subdivide the organ by separating one crypt from another.

Skeletal muscle and mucous glands occur deep to the capsule.

A large number of lymphatic nodules are present on this section. Many of them have germinal centers. The nodules usually lie as a single layer just beneath the epithelium surrounding each crypt. Only a loose layer of lymphatic tissue separates the nodules from the epithelium. With high power, note that deep in the crypts numerous lymphocytes have infiltrated the epithelium. In some deep areas of the crypts it is difficult to identify the type of epithelium. Observe that the surface epithelium is infiltrated by fewer lymphocytes.

Note that afferent lymphatic vessels and lymph sinuses as seen in lymph nodes are absent from tonsils.

Tonsils are not divided into a cortex and a medulla.

Reticular connective tissue forms the stroma of the tonsil, but the reticular fibers cannot be identified without special stains. The reticular cells are obscured by the lymphocytes.

<peir-vm>UAB-Histology-00052</peir-vm>

=== Aggregated nodules (Peyer’s patches) ===

Identify aggregated nodules on slide 31, 168, or 172 Ileum (H&E).

Aggregated nodules (Peyer’s patch) consist of groups of lymphatic nodules massed together in the wall of the ileum opposite the attachment of the mesentery. One Peyer’s patch may consist of ten to seventy lymphatic nodules.

The nodules originate in the lamina propria but they may extend into the submucosa disrupting the muscularis mucosae. Where the nodules project to the luminal surface of the ileum, villi are absent.

==== Slide 31: Ileum (H&E) ====
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==== Slide 168: Ileum (H&E) ====
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==== Slide 172: Ileum (H&E) ====
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== Spleen ==
[[File:HistologicChapter8Spleen.jpg|thumb|200px|Spleen]]
The spleen is an organ which both forms and destroys blood cells. In the embryo the spleen is a fully hemopoietic organ generating all the kinds of blood cells. In late fetal life the spleen stops producing erythrocytes and granulocytes, but it continues to generate lymphocytes and monocytes. However, it retains full hemopoietic potentialities so that pathologically, in adulthood, the spleen may once again initiate the functions of red bone marrow. The spleen is highly active in the production of antibodies. Plasma cells are the main source of the antibodies. The spleen also serves as a specialized blood-filtering organ and it can serve for the temporary storage of platelets and erythrocytes.

=== Slide 18: Spleen (H&E) ===

Examine slide 18, Spleen (H&E) and identify the capsule and trabeculae

The capsule is covered by mesothelium. The capsule is composed of collagen, elastic and a very few smooth muscle fibers. The elastic fibers predominate in the inner half of the capsule.

Note that the trabeculae appear to be cut at random and that they stain similar to the capsule since they are extensions of this structure into the substance of the spleen. Trabeculae form a supporting framework.

The amount of elastic tissue in the trabeculae is similar to that found in the inner half of the capsule. Note that some sections of the trabeculae show trabecular arteries and veins coursing through them. Neither demonstrates an adventitia; the connective tissue of the trabecula immediately surrounds the media.

Identify the darkly stained lymphatic nodules (splenic nodules) of the white pulp. Identify the central arteries passing through a lymphatic nodule. Note that diffuse to dense lymphatic tissue also occurs in the white pulp mainly surrounding and following the distribution of the arterial vessels. White pulp is typical lymphatic tissue containing a stroma of reticular cells and fibers.

Select a particularly dense or large lymphatic nodule to identify the marginal zone at its periphery. The marginal zone is a transitional region of red pulp containing more lymphocytes and plasma cells than the pulp cords. Branches from the central artery pass into this transitional zone. It is here that T- lymphocytes leave the general circulation to take up residence in the spleen.

The red pulp occurs mainly as venous sinuses and the intervening pulp cords. This tissue lies between the areas of the white pulp. There is no sharp boundary between red and white pulp. The red pulp is atypical lymphatic tissue. It has reticular connective tissue infiltrated with lymphocytes and monocytes, but in addition, all other kinds of blood cells occur here as well. Especially numerous are the erythrocytes which impart a reddish coloration to the area of the red pulp in the fresh spleen.

<peir-vm>UAB-Histology-00018</peir-vm>

==== Slide 19: Spleen (PASH) ====

The pulp cords consist of the tissue occupying the narrow areas between the venous sinuses. With high power, study the splenic sinuses and pulp cords. Note how much easier it is to identify the venous sinuses by using the PASH stained section of Spleen (slide 19, Spleen PASH).

<peir-vm>UAB-Histology-00019</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 7

2014-07-28T23:52:35Z

Seung Park:

== Introduction ==

The formed elements of blood, which are suspended in the fluid plasma, are: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. Several methods exist for studying the formed elements of the blood and serve various purposes. Clinically, the type of preparation used most often is the blood smear in which a drop of blood is spread on a slide and then stained, usually with Wright’s stain.

== Blood Smears ==

=== Slide 37: Blood Smear (Wright's stain) ===

Examine slide 37. This is a blood smear stained with Wright’s stain. Wright’s stain is a polychrome stain in wide use for fixing as well as staining smears of blood as well as exudates and protozoan parasites. Its staining action depends upon a combination of methylene blue and eosin, which stain both independently as well as synergistically. The solution thus contains three staining factors that color the various structures of the preparation selectively.

At 10x power note that in some areas of the slide the cells (predominantly erythrocytes) are spread far apart and in other areas may be piled on top of one another. In the former area the densely staining white blood cells are flattened out, while in the latter they are more nearly spherical and much smaller. The optimum area for observation is somewhere between these extremes.

In an optimum area, examine the cells at high power.

<peir-vm>UAB-Histology-00037</peir-vm>

=== Erythrocytes (red blood corpuscles) ===
[[File:HistologicChapter7RedBloodCells.jpg|thumb|200px|Red Blood Cells]]
[[File:HistologicChapter7RedBloodCellsMicroscope.jpg|thumb|200px|Red Blood Cells Microscope]]
Note the staining, size, and shape of these elements. Erythrocytes are biconcave discs that average 7.7μm in diameter and 1.9μm in the greatest thickness. Look at the scanning EM picture (below) to see the three dimensional appearance of erythrocytes. Adult men have an average of 5.5 million RBCs and 8 thousand white blood cells per cubic millimeter of blood; thus, only one leukocyte exists for every six to seven hundred RBCs.

Crenation of erythrocytes may be observed; this shrunken and indented appearance occurs when erythrocytes are in a hypertonic environment. In a hypotonic solution the erythrocytes may swell and rupture; this process is known as hemolysis. Rouleaux formation is the stacking of erythrocytes.

In certain kinds of anemias the RBCs may be larger than normal (macrocytes) or smaller than normal (microcytes). In normal blood the range in size of erythrocytes is very narrow with the differences in diameter usually being less than one micrometer.

=== Leukocytes (white blood cells) ===
[[File:HistologicChapter7WhiteBloodCells.jpg|thumb|200px|White Blood Cells]]
Leukocytes are divided into two major types: the granulocytes and the agranulocytes. The white blood cells are involved in inflammatory and immune reactions and function both within and outside of the bloodstream. In different disease states a marked increase in numbers of leukocytes above the normal range is called leukocytosis (10,000 or more per cu. mm) whereas a decrease below 5000 per cu. mm is called leukopenia.

Granular leukocytes (granulocytes) are the leukocytes that contain specific cytoplasmic granules, and they usually have a lobed nucleus. Because of this nuclear feature the granulocytes are often spoken of as being polymorphonuclear leukocytes. However, keep in mind that most hematologists and medical technicians use the terms “polymorphs” or “polys” for just the neutrophils. Although sometimes appearing separated from each other, the nuclear lobes are actually connected by thin delicate strands of nuclear material.

==== Neutrophils ====

In the normal, healthy individual neutrophils are the most common the leukocytes, making up 50 - 75% of the white blood cells. Between 3,000 and 6,000 neutrophils per cubic mm make up the normal range. They average 9 - 12 μm in diameter, usually contain 3 - 5 nuclear lobes and possess neutrophilic and azurophilic granules.

Study various neutrophils noting their size, shape, staining features, granularity, and nuclear configuration. Look for neutrophils with various numbers of nuclear lobes. The neutrophils with nonsegmented nuclei (“band forms” or “stabs”) in which the nucleus is simply elongate and/or horseshoe- shaped are younger cells than those in which the nucleus is differentiated into three, four or five lobes.

In approximately 3% of the neutrophils of females a nuclear appendage, like a small “drumstick” is present. This represents the inactive X sex chromatin comparable to the Barr body found in buccal smears and other cells.

Neutrophils act as the first line of defense against many invading organisms. We sometimes speak of neutrophils as being the tissue microphage since they mainly serve to phagocytize bacteria and small particles as compared with macrophages, which ingest much larger particles.

==== Eosinophils ====

These granulocytes constitute 2-4% of the leukocytes. They are close to the same size as the neutrophils or just slightly larger (10-15μm in diameter). Characteristic features of eosinophils include large coarse eosinophilic granules and a bilobed nucleus (usually). Eosinophils are important in engulfing antigen-antibody complexes. They increase markedly following certain allergic reactions and parasitic infestations. The eosinophilic granules function as large lysosomes; they give positive reaction for the common lysosomal enzymes and for peroxidase.

==== Basophils ====

Basophils are smaller than the other granulocytes being only 8-
10μm in diameter, and they are fewer in number making up only 0.5 to 1% of the leukocyte population. These cells are easily recognized in Wright-stained blood smears because of their coarse, large basophilic granules. These large, dark purplish granules may cover the nucleus that is often elongated and folded in the form of a “U” or an “S.” Basophils carry heparin and histamine in their granules.

=== Agranular Leukocytes ===

Agranular leukocytes (agranulocytes or round cells), are leukocytes that lack specific granules, although a few inconstant, non-specific granules do occur in the cytoplasm. The latter are mainly of lysosomal nature. Lymphocytes and monocytes make up the agranular leukocyte population of white blood cells.

==== Lymphocytes ====

In normal circulating blood 20 to 40% (1,000 to 3,000 per cu. mm) of the leukocytes are lymphocytes with the average being about 25%. In blood smears the small lymphocyte has an average diameter of 7-8μm with the size range being between 6-10μm. Traditionally, lymphocytes in blood have been considered as small, medium, and large. The latter are very difficult to distinguish from monocytes.

Two distinct populations of small lymphocytes occur in the blood stream (the T and B lymphocytes), but they cannot be distinguished on a morphological basis. However, they do differ in developmental background, in life span, and in their defensive roles in the immunological responses of the body.

Note the size, shape, and comparative numbers of the lymphocytes on your slide. Compare their size with nearby erythrocytes. The nucleus is nearly spherical or slightly indented, dense, dark and it is usually surrounded by a thin rim of basophilic-staining cytoplasm. The coloration of the cytoplasm in high quality Wright’s stained smears ranges from a clear blue color to a greenish blue.

==== Monocytes ====

This is the largest of the leukocytes. It ranges between 12 and 20μm and makes up 3-8% of the white cell population in a blood smear. It is often difficult to distinguish clearly between a monocyte and a large lymphocyte. Monocytes rarely have a spherical nucleus like the lymphocyte. Instead, the monocyte nucleus is usually oval or it is indented or horseshoe- shaped. Also, it tends to be eccentrically located and it stains lighter than the lymphocyte nucleus because the chromatin is less dense. Often the nucleus appears “wrinkled,” twisted or folded, and not as uniformly stained as the lymphocyte nucleus.

With Wright’s stain the cytoplasm is a grayish blue or a “muddier blue” than the lymphocyte cytoplasm. Nonspecific, azurophilic granules (lysosomes) occur in the monocyte cytoplasm.

Monocytes give rise to tissue macrophages. The average time spend in the blood stream for a monocyte is three days. Monocytes originate from stem cells in the red bone marrow.

Study the monocytes on your slide noting size, shape, granularity, and the coloration of the cytoplasm and nucleus.

==== Platelets ====

These are ovoid to round cytoplasmic fragments (not cells) derived from megakaryocytes of red bone marrow. Platelets average 3μm in diameter and number 200,000 to 300,000 per cu. mm. In blood smears platelets tend to clump together so they are difficult to count accurately. In making counts of platelets it is essential to draw the blood into a syringe or pipette containing antiagglutinins. Platelets function in agglutination (the clumping of platelets in flowing blood) by adhering to the injured walls of blood vessels. From this action the coagulation of blood occurs in which a meshwork of fibrin materializes and the blood becomes clotted.

The basophilic staining central region of a platelet is called the granulomere or chromomere because the cytoplasm here contains more granules and organelles than the peripheral cytoplasm, which is pale and homogenous. This thin peripheral zone of cytoplasm is called the hyalomere. It stains a pale blue. The characteristic granules of human platelets, called alpha granules, are approximately 0.2μm in diameter. The currently known list of alpha-granular proteins continues to enlarge and includes many adhesive proteins (e.g. Fg, von Willebrand factor (vWf) and thrombospodin (TSP)), plasma proteins (e.g. IgG and albumin), cellular mitogens (e.g. platelet derived growth factor and TGF beta), coagulation factors (e.g. factor V) and protease inhibitors (e.g. alpha 2-macroglobulin and alpha 2-antiplasmin). More recently the inner lining of the alpha-granule unit membrane has been demonstrated to contain a number of physiologically important receptors including glycoprotein IIb/IIIa (alpha IIb beta 3) and P-selectin.

=== Slide 8: Intervertebral Disc (H&E) ===

On slide 8, Intervertebral disc (H&E) find the red bone marrow and identify the megakaryocytes from which platelets are derived. Megakaryocytes are the largest cells found in normal bone marrow. The nucleus is multilobed and polyploid since chromosomal replications occur in these cells without cytoplasmic divisions.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Contributors

2014-07-28T23:51:27Z

Seung Park:

== Acknowledgements ==
This Virtual Microscopy Histology Laboratory Manual is a derivative work from the laboratory teaching materials produced over many years by anatomists from the University of Alabama at Birmingham School of Medicine. The instructors who designed the curriculum, acquired the teaching slide sets and developed this laboratory manual were: George Hand, PhD, Jim Sheetz, PhD and Laura Cotlin, PhD

The virtual microscopy slides described in this manual are primarily scans of original glass slides used in the University of Alabama at Birmingham School of Medicine Cell Biology and Histology teaching program. Additional virtual microscopy slides were kindly contributed by: James L. Fishback, MD, University of Kansas School of Medicine; Mary Ann Sens, MD, PhD, University of North Dakota School of Medicine; and Richard M. Conran, MD, PhD, Uniformed Services University of the Health Sciences. [http://peir-vm.path.uab.edu/ PEIR-VM], the universal web viewer for common whole slide imaging file formats used extensively in Histologic, is developed and maintained by a [http://peir-vm.path.uab.edu/contact.php team] lead by Seung Park, MD.

== Staff ==
=== Faculty Advisors ===
==== Molecular and Cellular Pathology ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=19493 Peter G. Anderson, DVM, PhD]

==== Pathology Informatics ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=61255 Seung Park, MD]

=== Residents, Fellows, and Students ===

==== Summer 2014 ====
* [http://bsc.ua.edu/undergraduate-studies/majors/ Matthew Anderson]
* [http://www.uab.edu/medicine/mstp/current-students Tim Kennell, BS]
* [http://www.uab.edu/medicine/pathology/residency-program/current-residents Alexander Feldman, MD]

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 19

2014-07-28T23:47:54Z

Seung Park: /* Slide 286, Ear Cochlea */

== Eye ==
[[File:HistologicChapter19EyeDiagramUveitis.jpg|thumb|200px|Eye Diagram Uveitis]]
=== Slide 285: Eye (H&E) ===

The eyeball is composed of three principal layers.

The outer layer, or sclera, consists of dense fibrous connective tissue. The sclera is the "white" of the eye. The sclera is continuous with the transparent substantia propria of the cornea. The exposed front surface of the eye, including the cornea, is also covered by a thin, non-keratinized stratified squamous epithelium.

The next layer, or choroid, consists of heavily pigmented loose connective tissue, including many melanocytes. The choroid is normally not visible behind the "white" of the sclera. The choroid is continuous with the iris; together the choroid and iris are called the uvea. A hole in this layer, the pupil, allows light to pass through.

The inner layer, or retina, includes two portions. The neural retina is the photoreceptive, imaging-processing tissue. And the pigmented epithelium lies behind the neural retina; it also extends forward to line the iris. The lens is a specialized epithelial structure, suspended behind the pupil.

The anterior chamber, the space between the iris and the cornea, is filled with aqueous humor. And the posterior chamber lies behind the iris.

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=== Cornea ===

The cornea consists of a thin surface epithelium (non-keratinized stratified squamous epithelium) overlying a layer of dense fibrous connective tissue, called the substantia propria. The epithelium of the cornea is continuous with the epithelium of the conjunctiva, both that of the eyeball itself and that of the inside of the eyelid; however the corneal epithelium is very thin (only a few cells thick) which leads to its transparency. The basement membrane between the corneal epithelium and the substantia propria is exceptionally thick and is called Bowman's membrane. Collagen of the cornea is organized into extremely regular layers. All the collagen fibers in one layer arranged in parallel, and alternating layers run in different directions. Corneal connective tissue has no blood vessels. Even though cells of the cornea are not very active metabolically, they still need oxygen and nutrients. As long as the cornea is in direct contact with air, oxygen can be absorbed directly and nutrients can diffuse into cornea from the aqueous humor. Cells of cornea are limited to fibroblasts and there are no blood vessels so there are no immune-system components; hence corneal tissue can be transplanted without need for careful tissue typing.

At the inner surface of the cornea, a thick basal lamina (Decemet's membrane) separates the substantia propria from a layer of simple low cuboidal epithelium, called the corneal endothelium.

Corneal epithelium contains free nerve endings. Since pain seems to be the only sensory modality that functions for corneal tissue, biologists long ago decided that free nerve endings elsewhere may also represent pain fibers.

=== Iris ===

Functionally, the iris is a rather simple opaque ring surrounding and controlling the diameter of its central aperture - the pupil. A ring of smooth muscle surrounding the pupil comprises the pupillary sphincter. The color of the iris ("eye color") results both from scattering of light by its trabecular meshwork of collagen fibers and from absorption of light by melanin granules in scattered melanocytes. Variations in eye color result from individual differences in the distribution and density of melanocytes and trabecular meshwork.

=== Lens ===

The lens is an isolated island of epithelial tissue with an anterior layer that is simple cuboidal and a posterior layer consisting of elongated cells, called lens fibers that are packed with lens protein. The shape of the lens (and hence its focal length) is determined by tension exerted through the suspensory fibers, controlled by smooth muscle of the ciliary body.

=== Ciliary Body and Suspensory Fibers (zonules) ===

Deep to the limbus (i.e., the site where the cornea meets the sclera), the choroid layer is thickened into the ciliary body. The ciliary body is a ring of smooth muscle fibers arranged concentrically around the opening in which the lens is suspended. The lens is suspended from the ciliary body by thin fibers of collagen, called suspensory fibers or zonules. Together, the ciliary body and suspensory fibers control the shape of the lens. The surface of the ciliary body is covered by an extension of the embryonic optic cup and small projections of this tissue from the ciliary processes, which secretes the aqueous humor. Aqueous humor flows from its site of formation in the posterior chamber (i.e., behind the iris) through the pupil into the anterior chamber. From there it drains into the canal of Schlemm and hence into venous drainage. An imbalance between the formation and drainage of aqueous humor can create increased pressure leading to glaucoma.

=== Retina ===
[[File:HistologicChapter19Retina.Jpg|thumb|200px|Retina]]
The retina consists of two distinct layers, the neural retina (often called simply "the retina") and the pigmented epithelium.

The neural retina is the light-sensitive tissue of the eye. The photoreceptor cells (rods and cones) are located in the back of the retina, so light must pass through all of the layers of the neural retina before getting to the receptors. And the blood vessels which serve the retina are spread across the front surface, so light on its way to the receptors must also pass by the blood vessels. The nerve fibers which eventually travel from the eye through the optic nerve must pass through the layers of the retina, leaving a "blind spot" where they do so.

Cells comprising the neural retina form several layers.

*The innermost layer is the inner limiting membrane, a basal lamina separating nervous tissue of the retina from connective tissue of the vitreous humor.
*The layer of nerve fibers contains axons from ganglion cells which travel across the retina to the optic nerve and hence past the optic chiasm into the optic tract and into lateral geniculate nucleus of the thalamus.
*The ganglion cell layer contains the cell bodies of ganglion cells, the cells whose axons project to the brain.
*The inner plexiform layer contains dendrites of ganglion cells synapsing with axons of bipolar cells.
*The inner nuclear layer contains the cell bodies of bipolar cells
*The outer plexiform layer contains dendrites of bipolar cells synapsing with axons of photoreceptor cells.
*The outer nuclear layer contains the cell bodies of receptor cells.
*Between the outer nuclear layer and the receptor layer is the site of the outer limiting membrane, a basal lamina bounding the neural retina.

The outer segments (rods and cones) of the receptor cells penetrate the outer membrane to contact the pigmented epithelium.

*The receptor layer contains the photoreceptive outer segments (rods and cones) of receptor cells.

Photoreceptor cells come in two types, rods and cones. Rods are sensitive to dim light and provide night vision. Rods are more numerous in the peripheral retina. Cones need brighter light and provide daytime color vision. Cones are more prevalent in the vicinity of the fovea.

== Ear ==
[[File:HistologicChapter19EarDiagram.jpg|thumb|200px|Ear Diagram]]
The ear has three distinct regions -- outer ear, middle ear, and inner ear.

The outer ear includes the pinna (the visible ear, consisting mostly of skin and cartilage) and the ear canal. The latter is lined by keratinized stratified squamous epithelium. This lining differs from skin by the presence of specialized ceruminous (ear-wax) glands.

The middle ear is basically a space, communicating via the eustacian tube with the oropharynx. It is lined by a very thin non-keratinized stratified squamous epithelium. Spanning the space of the middle ear are the three middle ear bones, the malleus (hammer), incus (anvil), and stapes (stirrup).

The eardrum is a thin membrane separating the outer ear from the middle ear. It is sandwich of tissues, with keratinized stratified squamous epithelium facing the outer ear, non-keratinized stratified squamous epithelium facing the middle ear, and a very thin layer of connective tissue in between.

The inner ear is the portion of the ear which contains sensory receptors.

=== Inner Ear ===

The inner ear consists of fluid-ﬁlled sacs (membranous labyrinth) that lie in cavities in the temporal bone of the skull (bony or osseous labyrinth). The inner ear contains sense organs serving both balance and hearing. Head position (i.e., gravity; also linear acceleration) is sensed by the otolith organs of the saccule and utricle. Head rotation (i.e., angular acceleration) is sensed by the cristae ampularis of the semicircular canals. And hearing is sensed by the organ of Corti within the scala media of the cochlea. All of these senses of the inner ear utilize the same mechanoreceptor cell type: epithelial hair cells.

Hair cells, the specialized mechanoreceptor cells of the auditory and vestibular systems, are found in several positions along the chambers and passageways of the membranous labyrinth. Hair cells are basically columnar epithelial cells. At the apical end of each hair cell is a set of "hairs" (cytoplasmic projections, kinocilium and stereocilia) embedded in a mass of extracellular jelly. At the basal end of each hair cell are synapses onto sensory axons. A hair cell responds when movement of the extracellular jelly displaces its kinocilium and stereocilia. Displacement of the kinocilium and stereocilia alters conductance of ion channels, in turn affecting release of neurotransmitter onto the associated sensory axon. (These axons project along the auditory and vestibular nerves, cranial nerve VIII).

=== Semicircular Canals ===

Each semicircular canal of the bony labyrinth is a hollow passageway looping out from and back to the vestibule. Within each of these passageways is a semicircular canal of the membranous labyrinth. At one end of each membranous semicircular canal is a small enlargement called the ampulla. Within each ampulla is a ridge or "crest" called the crista that is covered with hair cells. A small mass of jelly, called the cupola ("cap") rests on top of the hair cells of the crista. The hair cells of the ampullae respond to angular acceleration (i.e., rotation of the head)

There are three semicircular canals in each ear, oriented in three mutually-perpendicular planes. Rotation of the head in any direction will cause inertial fluid movement in one or more of the semicircular canals.

=== Cochlea ===
[[File:HistologicChapter19CochlearNerve.jpg|thumb|200px|Cochlear Nerve]]
==== Slide 286: Ear Cochlea (H&E) ====

The cochlea houses an elaborate configuration of membranous labyrinth and hair cells, called the organ of Corti, designed for auditory reception. The basic shape of the cochlea is that of a snail-shell, or tapering helix. The spiraling tunnel that forms the cochlea of the bony labyrinth is divided into three distinct channels by portions of the membranous labyrinth attached to bony ridges. The central column of the helical cochlea contains axons serving the organ of Corti on their way to the auditory nerve.

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=== Organ of Corti ===

The organ of Corti is an elaborate structure with more named parts than the rest of inner ear. The organ of Corti is a long strip of tissue that extends the length of the scala media, from the base of the cochlea to its apex. Within the complex strip of tissue that comprises the organ of Corti are specialized sensory hair cells. The whole organ of Corti rests on the basilar membrane which supports the basal ends of the hair cells in the organ of Corti. The apical ends of hair cells touch the tectorial membrane, a "shelf" of jelly that is supported immovably on the spiral lamina. When the basilar membrane flexes in respond to sound waves (i.e., pressure waves delivered to inner-ear fluid by the middle-ear ossicles), the organ of Corti, including its hair cells, also moves. Thus, when the basilar membrane is moved by pressure waves (i.e., sound), the hair cells move relative to the tectorial membrane, causing stimulatory deflection of the apical ends of the hair cells.

=== Endolymph and Perilymph ===
[[File:HistologicChapter19CristaAmpullaris.jpg|thumb|200px|Crista Ampullaris]]
The membranous labyrinth is filled with endolymph and is surrounded by perilymph. Endolymph is a unique fluid, with high K+ concentration and very low Na+ concentration. This endolymph provides the proper ionic environment for hair cell function. Endolymph is secreted by cells of the stria vascularis, along the scala media of the cochlea.

In the vestibular system (surrounding the saccule, utricle, and semicircular canals), perilymph simply provides a cushioning support for the membranous labyrinth.

In the cochlea, perilymph of the ascending scala vestibuli and the descending scala tympani conveys pressure waves (sound) across the scala media. Pressure waves flex the basilar membrane and thereby stimulate hair cells of the organ of Corti.

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 19

2014-07-28T23:47:34Z

Seung Park: /* Eye */

== Eye ==
[[File:HistologicChapter19EyeDiagramUveitis.jpg|thumb|200px|Eye Diagram Uveitis]]
=== Slide 285: Eye (H&E) ===

The eyeball is composed of three principal layers.

The outer layer, or sclera, consists of dense fibrous connective tissue. The sclera is the "white" of the eye. The sclera is continuous with the transparent substantia propria of the cornea. The exposed front surface of the eye, including the cornea, is also covered by a thin, non-keratinized stratified squamous epithelium.

The next layer, or choroid, consists of heavily pigmented loose connective tissue, including many melanocytes. The choroid is normally not visible behind the "white" of the sclera. The choroid is continuous with the iris; together the choroid and iris are called the uvea. A hole in this layer, the pupil, allows light to pass through.

The inner layer, or retina, includes two portions. The neural retina is the photoreceptive, imaging-processing tissue. And the pigmented epithelium lies behind the neural retina; it also extends forward to line the iris. The lens is a specialized epithelial structure, suspended behind the pupil.

The anterior chamber, the space between the iris and the cornea, is filled with aqueous humor. And the posterior chamber lies behind the iris.

<peir-vm>UAB-Histology-00285</peir-vm>

=== Cornea ===

The cornea consists of a thin surface epithelium (non-keratinized stratified squamous epithelium) overlying a layer of dense fibrous connective tissue, called the substantia propria. The epithelium of the cornea is continuous with the epithelium of the conjunctiva, both that of the eyeball itself and that of the inside of the eyelid; however the corneal epithelium is very thin (only a few cells thick) which leads to its transparency. The basement membrane between the corneal epithelium and the substantia propria is exceptionally thick and is called Bowman's membrane. Collagen of the cornea is organized into extremely regular layers. All the collagen fibers in one layer arranged in parallel, and alternating layers run in different directions. Corneal connective tissue has no blood vessels. Even though cells of the cornea are not very active metabolically, they still need oxygen and nutrients. As long as the cornea is in direct contact with air, oxygen can be absorbed directly and nutrients can diffuse into cornea from the aqueous humor. Cells of cornea are limited to fibroblasts and there are no blood vessels so there are no immune-system components; hence corneal tissue can be transplanted without need for careful tissue typing.

At the inner surface of the cornea, a thick basal lamina (Decemet's membrane) separates the substantia propria from a layer of simple low cuboidal epithelium, called the corneal endothelium.

Corneal epithelium contains free nerve endings. Since pain seems to be the only sensory modality that functions for corneal tissue, biologists long ago decided that free nerve endings elsewhere may also represent pain fibers.

=== Iris ===

Functionally, the iris is a rather simple opaque ring surrounding and controlling the diameter of its central aperture - the pupil. A ring of smooth muscle surrounding the pupil comprises the pupillary sphincter. The color of the iris ("eye color") results both from scattering of light by its trabecular meshwork of collagen fibers and from absorption of light by melanin granules in scattered melanocytes. Variations in eye color result from individual differences in the distribution and density of melanocytes and trabecular meshwork.

=== Lens ===

The lens is an isolated island of epithelial tissue with an anterior layer that is simple cuboidal and a posterior layer consisting of elongated cells, called lens fibers that are packed with lens protein. The shape of the lens (and hence its focal length) is determined by tension exerted through the suspensory fibers, controlled by smooth muscle of the ciliary body.

=== Ciliary Body and Suspensory Fibers (zonules) ===

Deep to the limbus (i.e., the site where the cornea meets the sclera), the choroid layer is thickened into the ciliary body. The ciliary body is a ring of smooth muscle fibers arranged concentrically around the opening in which the lens is suspended. The lens is suspended from the ciliary body by thin fibers of collagen, called suspensory fibers or zonules. Together, the ciliary body and suspensory fibers control the shape of the lens. The surface of the ciliary body is covered by an extension of the embryonic optic cup and small projections of this tissue from the ciliary processes, which secretes the aqueous humor. Aqueous humor flows from its site of formation in the posterior chamber (i.e., behind the iris) through the pupil into the anterior chamber. From there it drains into the canal of Schlemm and hence into venous drainage. An imbalance between the formation and drainage of aqueous humor can create increased pressure leading to glaucoma.

=== Retina ===
[[File:HistologicChapter19Retina.Jpg|thumb|200px|Retina]]
The retina consists of two distinct layers, the neural retina (often called simply "the retina") and the pigmented epithelium.

The neural retina is the light-sensitive tissue of the eye. The photoreceptor cells (rods and cones) are located in the back of the retina, so light must pass through all of the layers of the neural retina before getting to the receptors. And the blood vessels which serve the retina are spread across the front surface, so light on its way to the receptors must also pass by the blood vessels. The nerve fibers which eventually travel from the eye through the optic nerve must pass through the layers of the retina, leaving a "blind spot" where they do so.

Cells comprising the neural retina form several layers.

*The innermost layer is the inner limiting membrane, a basal lamina separating nervous tissue of the retina from connective tissue of the vitreous humor.
*The layer of nerve fibers contains axons from ganglion cells which travel across the retina to the optic nerve and hence past the optic chiasm into the optic tract and into lateral geniculate nucleus of the thalamus.
*The ganglion cell layer contains the cell bodies of ganglion cells, the cells whose axons project to the brain.
*The inner plexiform layer contains dendrites of ganglion cells synapsing with axons of bipolar cells.
*The inner nuclear layer contains the cell bodies of bipolar cells
*The outer plexiform layer contains dendrites of bipolar cells synapsing with axons of photoreceptor cells.
*The outer nuclear layer contains the cell bodies of receptor cells.
*Between the outer nuclear layer and the receptor layer is the site of the outer limiting membrane, a basal lamina bounding the neural retina.

The outer segments (rods and cones) of the receptor cells penetrate the outer membrane to contact the pigmented epithelium.

*The receptor layer contains the photoreceptive outer segments (rods and cones) of receptor cells.

Photoreceptor cells come in two types, rods and cones. Rods are sensitive to dim light and provide night vision. Rods are more numerous in the peripheral retina. Cones need brighter light and provide daytime color vision. Cones are more prevalent in the vicinity of the fovea.

== Ear ==
[[File:HistologicChapter19EarDiagram.jpg|thumb|200px|Ear Diagram]]
The ear has three distinct regions -- outer ear, middle ear, and inner ear.

The outer ear includes the pinna (the visible ear, consisting mostly of skin and cartilage) and the ear canal. The latter is lined by keratinized stratified squamous epithelium. This lining differs from skin by the presence of specialized ceruminous (ear-wax) glands.

The middle ear is basically a space, communicating via the eustacian tube with the oropharynx. It is lined by a very thin non-keratinized stratified squamous epithelium. Spanning the space of the middle ear are the three middle ear bones, the malleus (hammer), incus (anvil), and stapes (stirrup).

The eardrum is a thin membrane separating the outer ear from the middle ear. It is sandwich of tissues, with keratinized stratified squamous epithelium facing the outer ear, non-keratinized stratified squamous epithelium facing the middle ear, and a very thin layer of connective tissue in between.

The inner ear is the portion of the ear which contains sensory receptors.

=== Inner Ear ===

The inner ear consists of fluid-ﬁlled sacs (membranous labyrinth) that lie in cavities in the temporal bone of the skull (bony or osseous labyrinth). The inner ear contains sense organs serving both balance and hearing. Head position (i.e., gravity; also linear acceleration) is sensed by the otolith organs of the saccule and utricle. Head rotation (i.e., angular acceleration) is sensed by the cristae ampularis of the semicircular canals. And hearing is sensed by the organ of Corti within the scala media of the cochlea. All of these senses of the inner ear utilize the same mechanoreceptor cell type: epithelial hair cells.

Hair cells, the specialized mechanoreceptor cells of the auditory and vestibular systems, are found in several positions along the chambers and passageways of the membranous labyrinth. Hair cells are basically columnar epithelial cells. At the apical end of each hair cell is a set of "hairs" (cytoplasmic projections, kinocilium and stereocilia) embedded in a mass of extracellular jelly. At the basal end of each hair cell are synapses onto sensory axons. A hair cell responds when movement of the extracellular jelly displaces its kinocilium and stereocilia. Displacement of the kinocilium and stereocilia alters conductance of ion channels, in turn affecting release of neurotransmitter onto the associated sensory axon. (These axons project along the auditory and vestibular nerves, cranial nerve VIII).

=== Semicircular Canals ===

Each semicircular canal of the bony labyrinth is a hollow passageway looping out from and back to the vestibule. Within each of these passageways is a semicircular canal of the membranous labyrinth. At one end of each membranous semicircular canal is a small enlargement called the ampulla. Within each ampulla is a ridge or "crest" called the crista that is covered with hair cells. A small mass of jelly, called the cupola ("cap") rests on top of the hair cells of the crista. The hair cells of the ampullae respond to angular acceleration (i.e., rotation of the head)

There are three semicircular canals in each ear, oriented in three mutually-perpendicular planes. Rotation of the head in any direction will cause inertial fluid movement in one or more of the semicircular canals.

=== Cochlea ===
[[File:HistologicChapter19CochlearNerve.jpg|thumb|200px|Cochlear Nerve]]
==== Slide 286, Ear Cochlea ====

The cochlea houses an elaborate configuration of membranous labyrinth and hair cells, called the organ of Corti, designed for auditory reception. The basic shape of the cochlea is that of a snail-shell, or tapering helix. The spiraling tunnel that forms the cochlea of the bony labyrinth is divided into three distinct channels by portions of the membranous labyrinth attached to bony ridges. The central column of the helical cochlea contains axons serving the organ of Corti on their way to the auditory nerve.

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=== Organ of Corti ===

The organ of Corti is an elaborate structure with more named parts than the rest of inner ear. The organ of Corti is a long strip of tissue that extends the length of the scala media, from the base of the cochlea to its apex. Within the complex strip of tissue that comprises the organ of Corti are specialized sensory hair cells. The whole organ of Corti rests on the basilar membrane which supports the basal ends of the hair cells in the organ of Corti. The apical ends of hair cells touch the tectorial membrane, a "shelf" of jelly that is supported immovably on the spiral lamina. When the basilar membrane flexes in respond to sound waves (i.e., pressure waves delivered to inner-ear fluid by the middle-ear ossicles), the organ of Corti, including its hair cells, also moves. Thus, when the basilar membrane is moved by pressure waves (i.e., sound), the hair cells move relative to the tectorial membrane, causing stimulatory deflection of the apical ends of the hair cells.

=== Endolymph and Perilymph ===
[[File:HistologicChapter19CristaAmpullaris.jpg|thumb|200px|Crista Ampullaris]]
The membranous labyrinth is filled with endolymph and is surrounded by perilymph. Endolymph is a unique fluid, with high K+ concentration and very low Na+ concentration. This endolymph provides the proper ionic environment for hair cell function. Endolymph is secreted by cells of the stria vascularis, along the scala media of the cochlea.

In the vestibular system (surrounding the saccule, utricle, and semicircular canals), perilymph simply provides a cushioning support for the membranous labyrinth.

In the cochlea, perilymph of the ascending scala vestibuli and the descending scala tympani conveys pressure waves (sound) across the scala media. Pressure waves flex the basilar membrane and thereby stimulate hair cells of the organ of Corti.

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 16

2014-07-28T23:39:51Z

Seung Park: /* Slide 284, Penis (H&E) */

== Introduction ==

The components of the male reproductive system include the testes, the genital ducts, the accessory glands, and the penis.

== The Testis ==
[[File:HistologicChapter16Testis.jpg|thumb|200px|Testis]]
The testis functions as a cytogenic gland in that it produces spermatozoa and as an endocrine gland which produces the hormone testosterone. This hormone is essential for the proper development and maintenance of the accessory sexual organs, particularly the genital ducts and the accessory glands.

The two ovoid testes lie in the scrotum. Each testis is covered by three tunics.

*A prominent, tough, fibrous layer of connective tissue called the tunica albuginea forms the middle tunic.

*Investing the tunica albuginea is a layer of squamous cells and a thin layer of loose connective tissue, the tunica vaginalis, which represents a serous lining of peritoneum “trapped” by the descended testis. This tunic is lacking on the posterior wall of the testis.

*Internal to the tunica albuginea is a thin layer of loose, highly vascular connective tissue called the tunica vasculosa.

The testis is divided into about 250 anastomosing, pyramidal-shaped lobules by delicate connective tissue septa, the septulae testis. The septa radiate from the mediastinum into the testis. Within the testicular lobules occur from one to four convoluted seminiferous tubules where spermatozoa are produced.

The stroma of the testis lies between the seminiferous tubules. In addition to the usual connective tissue cells and collagenous fibers found in loose, vascular connective tissue, the stroma also contains endocrine tissue consisting of the interstitial cells (cells of Leydig). These cells produce the androgenic steroid hormone testosterone. Production of testosterone is stimulated by luteinizing hormone (LH = interstitial cell stimulating hormone, ICSH) produced by basophils of the anterior pituitary gland. Interstitial cells are polyhedral shaped cells (14 to 21 μm in diameter) with a large, rounded, sometimes wrinkled nucleus, and an acidophilic cytoplasm. The cytoplasm, in addition to the usual organelles, also contains a vast amount of smooth endoplasmic reticulum and mitochondria containing tubular cristae. These organelles are characteristic of cells which produce steroid hormones. Another cytoplasmic characteristic of interstitial cells are protein crystals (of Reinke) that vary in size, form and frequency of occurrence. The significance of these crystals is not clear.

A seminiferous tubule has a highly complex stratified epithelium consisting of spermatogenic cells and supporting cells (= sustentacular or Sertoli cells). External to the basement membrane on which the epithelium rests is a tunic of fibroelastic tissue. The supporting cells are tall, irregular columnar cells extending from the basement membrane to the lumen of the seminiferous tubule. On the lateral and apical surfaces, numerous recesses are formed by the plasma membrane which “indents” the cytoplasm. Within these recesses or depressions lie developing spermatogenic cells. The elaborate shapes of the supporting cells are difficult to see unless the testis has been prepared by a silver technique which demonstrates the cell boundaries. The large nuclei (9 to 12 μm diameter) of supporting cells have a variable position ranging from the basal zone to the mid- region of the cell. The nucleus is usually ovoid, stains palely, and shows an unusual tripartite nucleolus possessing a central acidophilic mass flanked by two basophilic masses. The nuclear membrane is frequently folded or longitudinally indented. The presence of moderate amounts of smooth endoplasmic reticulum and other features characteristic of steroid producing cells have led to suggestions that the supporting cells may produce steroid hormones. The major role of these cells is in mechanical support, protection, and perhaps nourishment of the developing germ cells.

=== Slide 227, Testis (H&E) ===

Scan this slide to observe:

Section of testis containing sections of seminiferous tubules. Note the dense tunica albuginea, the tunica vasculosa, the septula testis and the connective tissue stroma or interstitial tissue.

Identify the mediastinum testis containing the irregular channels of the rete testis.

A portion of the epididymis is present (the mass of tissue at one end) and can be seen containing efferent ducts and sections of the ductus epididymis. The former are in the uppermost area, the latter in the lowermost region.

Note the numerous blood vessels, nerves and abundance of connective tissue fibers and adipose tissue adjacent to the mediastinum and epididymis.

Study the normal seminiferous tubules. Locate the three layers that constitute the wall of a tubule. These are:

*An outermost layer of fibroelastic connective tissue.
*A basement membrane on which the spermatogonial and supporting cells rest.
*The complex stratified epithelium where spermatogenesis occurs.

The three layers may be seen more easily on slide 228, Testis (Masson) where the basement membrane is stained blue.

On slide 227, 228 and 230 identify the interstitial cells in the stromal tissue lying in angles between the seminiferous tubules. Interstitial cells are polyhedral in shape, have an acidophilic cytoplasm, and possess a rounded nucleus that usually contains one or two prominent nucleoli. The cytoplasm may be vacuolated where lipid droplets were dissolved away and an occasional cell may contain golden brown deposits of lipochrome pigment.

On the same slides, identify the supporting cells (Sertoli cells) within the stratified epithelium of the seminiferous tubules. Their cell boundaries will not be seen, but one usually can identify the nuclei of these tall columnar cells. The ovoid nucleus stains palely, contains a nucleolus and will occupy a variable position ranging from near the basement membrane to the middle of the cell.

Within the seminiferous tubules of slide 230 identify as many of the spermatogenic cells as possible.

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==== Slide 228, Testis (Masson) ====
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==== Slide 230, Testis ====
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== Genital Ducts ==

Straight tubules. On slide 227, Testis (H&E) identify the straight tubules located in a narrow region between the ends of the seminiferous tubules and the rete testis. The simple columnar epithelial cells, which line the initial segment of the straight tubules, resemble supporting cells. Near the rete testis the cells shorten to become cuboidal. These tubules have a uniformly narrow diameter.

Rete testis. The rete testis is located in the connective tissue of the mediastinum testis. It is that portion of the genital ducts which unites the straight tubules (tubuli recti) with the efferent ducts. The rete testis is essentially a system of anastomosing channels of epithelial lined spaces within connective tissue. As such the epithelium of these irregular spaces consists of low simple cuboidal to simple squamous cells resting on a basement membrane. A single cilium may occur on some of the cells. (Not seen on our slide.) A distinct lamina propria and muscularis are lacking. On slides 227 and 230 locate and study the rete testis in the dense connective tissue of the mediastinum. On these slides, its extent varies from extensive to virtually absent.

Efferent ducts. Efferent ducts (ductuli efferentes). About twelve to fifteen ductules (0.6 mm in diameter, 4 to 6 mm long) called efferent ducts unite the rete testis with the ductus epididymis. The ductules emerge from the mediastinum to the surface of the testis where they form cone-shaped coils that constitute much of the head of the epididymis. The efferent ducts consist of an epithelium resting on a thin basement membrane and some circularly oriented smooth muscle fibers embedded within the connective tissue surrounding the ductules.

On slide 227, Testis (H&E), and slide 230, Testis, (H&E) locate the efferent ducts in the epididymal region by the scalloped or undulated appearance of the epithelium. They appear in the lower right field on slide 227 and in the upper right field on slide 230. The epithelium is pseudostratified with small basal cells near the basement membrane and larger columnar or cuboidal surface cells. This gives the luminal surface of the ducts an irregular contour. The columnar cells are usually ciliated, whereas microvilli extend into the lumen from the cuboidal cells. (Cilia and microvilli are difficult to see on our slide.) Transport of sperm to the ductus epididymis is facilitated by the beating of the cilia. Motile cilia in the male genital ducts are found here and in the rete testis. The microvilli probably serve an absorptive function. Pigment granules and pale secretion granules may sometimes be seen in both types of surface cells of the ducts. Also, clear areas occur within the cells where fat has been dissolved away. On the upper right edge of slide 230 is a long, cystic tubule, probably an efferent duct that became obstructed.

Ductus epididymis. The epididymis lies on the posterior side of the testis. The ductus epididymis consists of a highly coiled duct (or tube) five to six meters in length, surrounded by smooth muscle and connective tissue. It occupies the body and the tail of the epididymis. The ductus epididymis unites proximally with the efferent ducts and distally with the ductus deferens. The duct is lined with a pseudostratified columnar epithelium consisting of tall columnar cells and smaller rounded basal cells. Large, nonmotile, branching microvilli called stereocilia extend from the apices of the columnar cells. Within the cytoplasm of these cells are secretory granules or vacuoles and pigment. Surrounding the epithelium is a thin lamina propria encircled by a very thin layer of smooth muscle. Outside the smooth muscle lies loose to compact connective tissue that forms the interstitium or stroma of the epididymis.

=== Slide 229, Ductus Epididymis (Masson) ===

Observe:

That numerous coils of the duct have been sectioned in various planes.

The relatively smooth lumen of the duct, owing to the uniform thickness of the epithelium and the stereocilia extending into the lumen.

The sperm stored within the lumen.

The scant amount of stromal connective tissue and smooth muscle surrounding the various coils of the duct.

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=== Slide 6, Ductus Epididymis (H&E) ===

Note especially the pseudostratified columnar epithelium possessing tall stereocilia.

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=== Slide 230, Testis (H&E) ===

Study slide 230, Testis (H&E) for comparison of efferent ducts and ductus epididymis.

Locate the numerous sections of the ductus epididymis (lower right field in both slides). Again, note the relatively smooth outline of the luminal surface of the ductus epididymis. Compare the appearance of this duct with the scalloped appearance of the efferent ducts previously studied on these slides (in the upper fields) especially on slide 230 where the latter are more numerous.

Ductus deferens. During development the testis descends from its early position on the posterior abdominal wall into the pelvis, and later during the seventh month of fetal life, it passes through the inguinal canal into the scrotum. Upon descending, each testis “pulls along” its vessels, nerves and ducts (ductus deferens) with it. These structures constitute the spermatic cord. The components of the spermatic cord are surrounded by connective tissue layers (fascia of gross anatomy) and by a somewhat discontinuous, longitudinally oriented layer of striated muscle fibers of the cremaster muscle.

The constituents of the spermatic cord are the:

*ductus deferens
*artery of the ductus deferens
*testicular artery
*cremasteric artery
*pampiniform plexus of veins
*lymphatic vessels
*nerves of the testis and epididymis

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=== Slide 232, Spermatic Cord (H&E) ===

Scan the tissue to observe:

*The large ductus deferens with its thick muscular coat.

*The numerous veins which constitute the pampiniform plexus. Some of these veins have unusually thick muscular tunics and bundles of longitudinally oriented muscle in the adventitia (medium-sized veins).

*Arteries

*Nerves

*Connective tissue fibers and adipose tissue of the fascial layers.

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== Accessory Glands ==

=== Prostate Gland ===
[[File:HistologicChapter16Prostate.jpg|thumb|200px|Prostate]]
The prostate gland is an accessory, unpaired sex gland of males that surrounds the urethra as it leaves the bladder. The prostate is an aggregation of 30 to 50 branched tubuloalveolar glands that secrete a milky fluid rich in citric acid and acid phosphatase. Grossly, the prostate gland has five lobes and is about one and a half inches in diameter. It is surrounded by a fibromuscular capsule.

The individual glands making up the overall prostate are arranged into a mucosal, a submucosal, and a main group of glands. They lie embedded in a fibromuscular stroma. The prostatic urethra traverses the prostate gland from superior to inferior surfaces. On each side of the prostatic utricle (the male homologue to the vagina) are located the ejaculatory ducts which open into the prostatic urethra. The ejaculatory ducts and the prostatic utricle are located in the seminal colliculus, an elevated portion of the urethral crest. The urethral crest is a longitudinal ridge that forms the posterior wall of the prostatic urethra.

==== Slide 123, Prostate (H&E) ====

Study Slide 123, Prostate (H&E) which is a section of the prostate from a 26- year-old male. Under low power note the numerous glands surrounded by the fibromuscular stroma. These glands are from the main group of glands of the prostate. Study them for detail noting that:

The epithelium is low pseudostratified, having columnar cells and basal cells resting on a thin basement membrane (not seen here). The apices of the columnar cells appear “washed out” (poorly stained) indicating that some of the secretory material has been lost in fixation and/or that the secretory droplets stain poorly with H&E. The apices of most of the secretory cells stain positively with lipid stains.

The epithelium shows numerous folds. Some of the folds have been sectioned tangentially and here the epithelium appears stratified. In other areas, the folds are cut through and appear as small “isolated islands” of epithelium.

Eosinophilic prostatic concretions (corpora amylacea) can be seen within the lumina of the glands. These rounded bodies increase with age following adulthood. They contain carbohydrate and protein and may become large enough to occlude the lumens of the glands. When calcified they are called calculi.

Study the abundant fibromuscular stroma making up about one-fourth to one-third of the gland. Strands of smooth muscle varying in thickness are intermixed with collagenous and elastic fibers. The muscle does not appear to have definite orientation or layers. This fibromuscular stroma is a distinctive feature of the prostate.

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==== Slide 124, Prostatic Urethra (H&E) ====

On slide 124, Prostatic Urethra (H&E), the general distribution of the somewhat concentrically arranged mucosal, submucosal and main prostatic glands can be studied. Identify these glands according to their locations.

The mucosal glands are smallest and are periurethral in position (next to the urethra). Their ducts open at various points into the urethra. (These are small, few in number and may be absent on your section.)

The submucosal glands are immediately peripheral to the mucosal ones, and the main glands which are largest and most numerous, lie to the outside of the submucosal glands on the periphery of the section. The ducts of the submucosal and main glands open into the urethral sinuses.

Abnormalities are present. Some of the main glands show cystic dilations.

The epithelium of these cystic glands is less folded than in the normal glands and in some regions appears to be squamous and less secretory than normal. Some glands may show lymphocytic infiltration. Others have stratified epithelium (hyperplasia).

Study the prostatic urethra, a U-shaped groove in the prostate, and the urethral crest, a longitudinal ridge that forms the posterior wall of the prostatic urethra. The posterolateral portions of the urethra on each side of the urethral crest are the urethral sinuses. It is here where the ducts of the submucosal and main glands empty secretions into the urethra.

Note the epithelium of the urethra. It is usually classified as transitional epithelium but patches of stratified columnar epithelium may be present.

Most slides do not have ejaculatory ducts or the prostatic utricle since the section was taken through the prostate superior to the entrance of these structures into the urethra, but parts of these two structures may be present. The part of the urethral crest in which the prostatic utricle is located is the colliculus seminalis.

Observe the periurethral vascular supply and the venous plexuses in the urethral crest.

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=== Seminal Vesicles ===

The seminal vesicles are paired saccular organs each in the form of a convoluted tube. They lie posterior to the prostate and their secretions, rich in fructose, enter the ejaculatory ducts just below the ampulla of the ductus deferens. The three layers of the gland are a mucosa, a muscularis and an adventitia (= fibrosa). The single lumen is irregular and branching with numerous lateral outpocketings.

==== Slide 237, Seminal Vesicle (H&E) ====

Observe that the gland appears to possess numerous lumina. Actually only one continuous cavity is present, but when the numerous convolutions of the gland are cut in one plane, separate cavities appear to be present.

Note the complicated folding of the mucosa in which thin primary folds often exhibit secondary and tertiary branching.

The muscularis contains an inner circular and an outer longitudinal layer of smooth muscle; two layers are not easily distinguishable in a section.

The adventitia or fibrosa is rich in elastic fibers. It contains large blood vessels, nerves, and blends with other connective tissue surrounding the gland. One or more ganglia may be present.

With high power study the mucosa on slide 237. The epithelium may appear to be simple cuboidal or low columnar, but the presence of basal cells makes it a low pseudostratified epithelium. The lining cells are secretory. A few granules may be present, or vacuoles may occur where they were dissolved away. Look for yellow or brownish lipochrome pigment in the surface cells. This pigment gives a yellowish tinge to the viscid secretions coming from these glands. The pigment begins to appear at puberty and increases with age. Beneath the epithelium is a basement membrane and a thin lamina propria with abundant elastic fibers.

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=== Bulbourethral Gland ===

==== Slide 238, Bulbourethral Gland (Masson) ====

Scan Slide 238, Bulbourethral gland (Masson) to observe that:

The irregular lobules of this compound tubuloalveolar gland are separated from each other by connective tissue septa that extend inward from a thin capsule.

At the periphery of the gland and also in the connective tissue septa between some of the lobules can be seen skeletal muscle fibers.

Interlobular excretory ducts lie within some of the larger connective tissue septa. (See e below)

With high power study the parenchyma consisting of pale secretory cells, usually cuboidal to columnar in shape. They resemble mucous cells. The nucleus tends to be flattened at the base of the cells; however, some are rounded, others are oval and vertically oriented. The varying shapes of the nuclei probably indicate different states of secretory activity exhibited by the cells at the time of fixation. A mucus-like discharge from these glands lubricates the urethra during sexual simulation.

In the smaller ducts of the bulbourethral gland the epithelium is simple and quite variable ranging from low cuboidal to columnar. The large excretory ducts are lined by stratified columnar epithelium that may contain patches of secreting cells. Smooth muscle fibers can usually be found among the connective tissue fibers surrounding these ducts and also in other regions of the connective tissue septa.

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== Penis ==

=== Slide 284, Penis (H&E) ===

The penis is composed of erectile tissue and contains the section of penile urethra. The erectile tissue is composed of two dorsal cylinders (corpora cavernosa) and a smaller central ventral cylinder (corpus spongiosum) through which the penile urethra runs. These cylinders are each surrounded by a dense fibrocollagenous sheath, the tunica albuginea. The erectile tissues are essentially interconnecting vascular spaces which are empty when the penis is flaccid but which become engorged with blood during an erection.

The blood supply to the penis is provided by the dorsal and the deep arteries. From the deep arteries arise arteries supplying the tunica albuginea, and the helicine arteries, which supply the erectile tissue. The helicine arteries form convoluted vessels in the flaccid penis but during erection they straighten and dilate, filling the corpora with blood. This filling effect is partly due to closure of the arteriovenous shunts existing between the helicine arteries and deep veins, which constitute the normal route of helicine artery blood flow in the flaccid state. Parasympathetic nerve discharges cause the closure, leading to diversion of the helicine artery blood into the cavernous spaces, while increased pressure in the corpora compresses the thin-walled veins, preventing emptying. After ejaculation the parasympathetic stimulation ceases, the arteriovenous shunts open and blood passes from the corpora into the veins.

At the distal end of the penis the corpus spongiosum terminates on the glans penis, which is covered with non-keratinizing squamous epithelium containing sebaceous glands. The penile urethra opens to the exterior at the meatus at the centre of the glans penis

For most of its length the penile urethra is lined by non-secreting columnar epithelium into which small mucus glands embedded in the corpus spongiosum drain. Within the glans penis, however, the urethra dilates (navicular fossa) and becomes lined by non-keratinizing stratified squamous epithelium identical to that covering the glans.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 17

2014-07-28T23:38:58Z

Seung Park: /* Slide 277, Umbilical Cord at term (H&E) */

== Introduction ==

The female reproductive system consists of the ovaries, the two uterine tubes (oviducts or Fallopian tubes) a uterus, a vagina, the external genitalia and the mammary glands. Normally, the development of this system requires that the zygote have the XX sex chromosomal complement. The ovaries produce the ova or female germ cells and certain hormones; the uterine tubes are necessary for transporting sperm to the ova for fertilization and for transporting the zygote to the uterus. Growth and maturation of the conceptus occur in the uterus. The vagina and external genitalia are the copulatory organs and the mammary glands serve for nutrition of the newborn.

== Ovary ==
[[File:HistologicChapter17Ovary.jpg|thumb|200px|Ovary]]
With the exception of slide 255, Monkey ovary (PASH), all other slides were obtained from human sources.

Study first slide 255 since it shows all the representative stages of follicle development. Then study slide 251, Ovary, (H&E); it has very small normal follicles, larger atretic follicles and corpora albicantia. Slide 254 Ovary (Masson) shows a large well-developed corpus luteum and a small atretic follicle with a prominent glassy membrane.

=== Slide 255, Ovary (PASH) ===

Slide 255, Ovary (PASH) shows a mature ovary with one large corpus luteum, several large preovulatory follicles, smaller growing follicles, and atretic follicles. Only a portion of the whole ovary is on the slide.

Study the cortex of the ovary.

Identify the surface epithelium (germinal epithelium), the tunica albuginea (a zone immediately beneath the surface epithelium which is more compact and less cellular than the stroma) and the stroma of cellular connective tissue.

Study the various stages of follicles.

Primordial (unilaminar follicles) consists of a small primary oocyte surrounded by a single layer of squamous follicular cells which rest on a basement membrane.

A primary follicle contains an enlarging oocyte surrounded by a single layer of flattened, cuboidal or low columnar follicular cells. These cells give rise to granulosa cells by mitosis.

Growing or multilaminar follicles are surrounded by several layers of follicular cells.

Vesicular (secondary or antral) follicles consist of a primary oocyte surrounded by 6-12 layers of granulosa cells. Fluid-filled spaces that appear between the granulosa cells gradually enlarge, interconnect, and eventually form a crescent-shaped cavity, the antrum.

Note the PAS-positive staining basement membrane located between the outer row of granulosa cells of the follicle and the stromal cells. Observe that the stromal cells are organized as a sheath of cells around the growing follicles.

The vesicular follicles are surrounded by a stromal sheath called the theca folliculi; the theca is divided into two regions, a theca interna and a theca externa.

The theca interna is a zone of epithelioid stromal cells surrounding the outer granulosa cells but separated from them by the basement membrane; this portion of the theca is vascular, containing capillaries and smaller blood vessels.

The theca externa lies external to the theca interna and consists of condensed stroma.

As the follicle enlarges, so does the oocyte. Increase in volume of both the nucleus and the cytoplasm accounts for oocyte enlargement. Observe the prominent nucleolus and the nuclear membrane of the oocytes; note that the cytoplasm is weakly acidophilic.

The zone pellucida is a prominent PAS-positive staining membrane immediately surrounding the oocyte’s plasma membrane. It is not present in primordial follicles or in smaller growing follicles.

The degeneration of follicles is called atresia and signs of this activity can be identified as follows:

*The granulosa cell layer may be partially detached from the theca interna.
*Groups of cells with pyknotic nuclei appear in the granulosa layer.
*Fragmentation of the oocytes may be occurring.
*The oocyte nucleus may be pyknotic (highly condensed and dark staining).
*The basement membrane is very irregular, wavy, and fragmented.
*The zone pellucida is fragmented or broken in places.

Study the vesicular (secondary or antral) follicles.

Identify early antrum formation in which the follicular cavity is small. Call-Exner bodies may be present between granulosal cells; they are strongly PAS-positive.

Find a large follicle (large antrum) in which the large volume of the antrum indicates it is filled with fluid called liquor folliculi.

The cumulus oophorus is a mound or hill of granulosa cells surrounding and supporting the large oocyte. This structure is present in the mature (Graafian) follicle.

The corona radiata is a cluster of granulosal cells which immediately surrounds the zona pellucida. When the ovum breaks free from the cumulus oophorus the corona radiata cells “go with it” and surround the ovum during ovulation and transport into the uterine tube.

Recall that just prior to ovulation, the primary oocyte undergoes its first maturation division, giving off the first polar body, to form a secondary oocyte. The final maturation division will not occur unless fertilization ensues.

Study the corpus luteum.

A corpus luteum is a new endocrine organ that makes its appearance after ovulation. The granulosa cells of the follicle hypertrophy, become luteinized and form granulosa lutein cells which secrete primarily progesterone. The corpus luteum on this slide is in an early stage of development. Note its large size. It consists of a thick folded wall and a central cavity (the former antrum of the follicle) which is filling in which fibrin deposits and loose connective tissue growing in from the theca externa.

Most of the wall is composed of granulosa lutein cells derived from the granulosa cells of the mature follicle. They are large cells with pale cytoplasm and a vesicular nucleus containing a prominent nucleolus. The cell membrane is stained with PAS. The cells are packed closely together, but fibroblasts, fine connective tissue, and capillaries invading from the stroma are penetrating between the cells toward the central cavity.

The theca lutein cells form a thin zone at the periphery of the corpus luteum and extend into the folds (which were formed when the ruptured follicle collapsed). They are not too apparent with this stain, but they are smaller cells than granulosa lutein cells.

The former antrum has fibrin deposits and is filling in with loose connective tissue.

The remains of atretic follicles can be seen as small irregular, intensely stained PAS-positive structures that are hypertrophied zona pellucida remnants from atretic follicles. They may or may not be surrounded by a greatly thickened folded glassy membrane (basement membrane) which stains pink. Both structures will be replaced by stroma.

Study the medulla of the ovary.

The medulla contains fibroelastic tissue, many large and smaller vessels, nerves, and lymphatics. Most of the blood vessels are highly coiled or convoluted.

The medulla is continuous with the connective tissue of the mesovarium, a short peritoneal fold that attaches the ovary to the broad ligament; the point of attachment serves as a hilus for the ovary. The mesothelium of the serosa (visceral peritoneum) of the mesovarium is continuous with the surface epithelium of the ovary.

A homologue to the rete testis in the male, the rete ovarii, can be seen in one part of the medulla (upper left in the field). They are distinguished by small, deeply basophilic nuclei of cuboidal cells lining an irregular-shaped lumen.

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=== Slide 251, Ovary, Human (H&E) (From an elderly woman) ===

Study the cortex of this ovary.

Note the prominent tunica albuginea just underneath the surface epithelium. The single layer of simple cuboidal cells making up the surface epithelium is present only in patches since part of it was sloughed off during preparation of the tissue.

The stroma is much more evident on this slide as compared with the monkey ovary just studied. Note the swirling pattern of the stromal cells, especially how they begin to swirl and encircle a follicle some distance from the follicle. In growing follicles, the stromal cells begin to condense into the thecal follicular sheath of cells that contribute to the function of the follicle.

Find primordial, primary and small growing follicles; (Primordial follicles are rare in mature ovaries). Note those follicles that show signs of atresia.

The two or three large follicles (preovulatory follicles) on this slide are also in early atresia. Granulosa cells have sloughed off or are still sloughing; the basement membrane in one follicle is beginning to hypertrophy.

Look for parts of corpora albicantia (singular = corpus albicans) which are fibrous scars that replace regressed corpora lutea; they are composed of compact collagenous fibers and fibroblasts, and have indefinite borders which merge with the stroma

Study the medulla of this ovary.

Note numerous, prominent blood vessels of various caliber which take up most of the volume of the medulla. Some of these vessels are quite convoluted (a long row of cross-sections of a vessel, each cross-section of about the same diameter, may be observed.

Lymphatics are also a prominent feature of the ovarian medulla. They are more difficult to distinguish because their thin walls may have collapsed, eliminating the lumen.

Vasomotor nerves to the smooth muscles of blood vessels may be seen; they are too small to see clearly.

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=== Slide 254, Ovary, Human (Masson) ===

The principal structure occupying most of this section is a corpus luteum. Other follicles may also be present, but concentrate on the corpus luteum.

The corpus luteum represents a very young stage of development, soon after ovulation. The amount of connective tissue located in the middle of the corpus luteum indicates the age of the organ. Note the huge size of the corpus luteum; it occupies most of the section.

Observe again that granulosa lutein cells make up the bulk of the corpus luteum; these are large cells with granular cytoplasm, vesicular nuclei and prominent nucleoli. Due to artifact of preparation or postmortem changes the cells are separated from each other by spaces.

The granulosa lutein cells are arranged into groups separated by delicate strands of connective tissue and capillaries.

In the central cavity are strands of clotted blood (red blood corpuscles and precipitated fibrin) and fine fibrin filaments. Little or no connective tissue is present as yet.

Numerous dilated blood vessels are seen in the stroma around the periphery of the corpus luteum, probably still in this state from their preovulatory condition.

The blue-staining connective tissue on the outer margin of the corpus luteum represents the former theca externa.

Theca lutein cells are present on the periphery and in the folds of this corpus luteum but are not yet well differentiated, thus are not easily identified. Blood vessels and connective tissue will be growing in from the former theca externa.

If fertilization does not take place, the corpus luteum persists for about two weeks, and then it breaks down (regresses) to become a corpus albicans. The corpus luteum in this case is called a corpus luteum spurium (false) or corpus luteum of menstruation.

If fertilization occurs, the corpus luteum persists, gets larger, and lasts longer; it is now called a corpus luteum verum (true) or corpus luteum of pregnancy.

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== Uterine Tube ==

Each uterine tube is about 12 cm long and serves to connect the uterus with the ovaries for transport of spermatozoa, fertilization of the ovum and nourishment and transport of the zygote. The uterine tube is embedded in (courses through) the mesosalpinx which is the upper part of the broad ligament of the uterus. Within this mesentery of the uterine tube is a central core of connective tissue, some smooth muscle, blood vessels and nerves, and it is covered by a serosa (peritoneum). Thus the wall of the uterine tube consists of three layers: a mucosa, a muscularis and a serosa.

Four regions of the uterine tube are generally recognized; from the uterus distally they are the interstitial (intramural) segment, the isthmus, the ampulla and the infundibulum. Only two regions or segments are represented in these slides. These are slides of the ampulla (slides 256, 257 and 258 and of the isthmus (slide 259).

=== Slide 257, Uterine Tube Ampulla (Masson) ===

Study the mucosa (mucous membrane) of this section of the uterine tube; note the complex foldings of the mucosa. The epithelium is actually simple columnar, but it frequently appears pseudostratified. It is tallest in the ampulla and decreases in height towards the uterus.

The epithelium consists of two types of cells, ciliated columnar cells (numerous on the fimbria and in the ampulla) and non-ciliated columnar secretory cells (peg cells).

The thin lamina propria is a primitive type of connective tissue, quite cellular; it extends into the folds. It is loosely arranged in the ampulla and is quite vascular. (It undergoes a decidual reaction, resembling decidual stromal cells found in the endometrium of the pregnant uterus, when tubal pregnancy occurs).

Observe the muscularis (muscular coat). It has two ill-defined smooth muscle layers; the inner spiral circular layer is thicker than the outer longitudinal muscle layer. Fine connective tissue intermingles with smooth muscle cells.

Surrounding the muscularis and intermingling with it is vascular connective tissue of the mesosalpinx. Note here the numerous greatly congested blood vessels of various diameters. Such congestion usually indicates a preovulatory state. A serosa forms the outermost layer.

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=== Slide 258, Uterine Tube, Ampulla (PASH) ===

This section of uterine tube is also from the ampulla in a pre-ovulatory state.

The two epithelial cell types can be identified; there appear to be fewer ciliated cells (may be post-mortem loss). PAS clearly demonstrates basement membranes of the epithelial cells as well as elastic membranes in blood vessels.

In the lamina propria, the looseness of the connective tissue in the folds is better demonstrated than in slide 257. Note branched fibroblasts and scattered lymphocytes. Lymphocytes may also be seen migrating through the epithelium to be eliminated from the body. Many dilated blood vessels are seen in this region.

The muscularis appears as patches of smooth muscle fibers dispersed among a loose arrangement of connective tissue fibers. Numerous dilated blood vessels are interspersed in the connective tissue among the bundles of muscle fibers.

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=== Slide 256, Uterine Tube (Ampulla) of Pregnancy (Masson) ===

This section represents uterine tube removed from a pregnant woman. There are artifactual breaks in the tissue section.

Identify the cell types in the epithelium. Nonciliated peg cells are most predominant, but this varies from place to place. The connective tissue of the lamina propria has proliferated to appear more like a primitive connective tissue; lymphocytes are more numerous. In the connective tissue you may be able to see large, pale-staining decidual cells which look like macrophages. These are glycogen storing cells that occur in great numbers in the uterus during pregnancy.

Lymphocytes, decidual cells, and other cells appear to be working their way between the epithelial cells into the lumen, probably a reaction to an interrupted pregnancy. They are surrounded by a vacuole.

Identify the layers of smooth muscle forming the muscularis, the numerous blood vessels in the connective tissue between the muscle bundles, and serosa covering most of the section.

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=== Slide 259, Uterine Tube (Masson) ===

This section is from the isthmus segment of the uterine tube, which lies along the uterine wall. Compare with slide 257, ampulla.

Observe the size of the lumen, the degree of mucosal folding, the height of the epithelium and the width of the lamina propria and the muscularis. The mucosal foldings are much less complex than in the ampulla.

Due to the thickness of this section of uterine tube its epithelium appears to be pseudostratified tall columnar. The nuclei are elongated and a few cells appear ciliated.

The lamina propria is more compact in the isthmus than in the folds of the ampulla.

Compare this section with that of the ductus deferens (slide 232) with which it might be confused. One should be able to distinguish them by the epithelium and by the layers of muscle.

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== Uterus ==
[[File:HistologicChapter17Uterus.jpg|thumb|200px|Uterus]]
The uterine slides demonstrate two phases of the menstrual cycle and one of pregnancy. No slides are available from premenstrual and menstrual phases of the uterus.

Slide 278 (H&E) is from the early proliferative phase.

Slide 261 (H&E) is from the proliferative phase.

Slide 262 (H&E) is from the secretory phase.

Slide 264 (PASH) is from pregnant uterus; it shows decidual cells in the stroma and also has some placenta attached to it.

=== Slide 278, Uterus, cross-section (H&E) ===

Slide 278, Uterus, cross-section (H&E), shows endometrium in early to mid- proliferative phase of the menstrual cycle (days 7 to 9).

Identify: endometrium (mucosa), myometrium (muscularis), and perimetrium (serosa).

Study the endometrium.

Distinguish two zones in the endometrium:

*The basalis (deep layer) where the stroma is compact and glands are branched.

*The functionalis, the entire endometrium above this. The stroma is not as compact as in the basal layer, but is quite dense in comparison with endometrium in later phases of the cycle.

Note the simple columnar surface epithelium; it may appear pseudostratified but all nuclei are similar, therefore all cells are columnar. Occasional lymphocytes lying in a small vacuole are seen in the columnar cells.

Simple tubular glands indent from the surface epithelium and extend through the thickness of the endometrium, becoming branched in their deepest parts. Some glands may extend into the myometrium for a short distance. The glandular epithelium is simple columnar that may also appear pseudostratified. Cytoplasm is very granular. Nuclei are basally located. Epithelium is proliferating; look for mitotic figures.

The stroma is a “cellular” connective tissue, with fibroblasts with large oval nuclei and branching cell processes embedded in fine collagenous and reticular fibers. It resembles embryonic connective tissue. Some proliferation of fibroblasts is still in progress; look for mitotic figures. Some lymphocytes are present, especially in the most peripheral stroma. Note that the stroma is denser in the basal layer. This region remains relatively inactive.

Look for coiled arteries in the lower fourth or third of the endometrium. Later, they will extend almost to the surface. A group of cross sections of these arterioles or very small arteries represents one coiled artery. Capillaries and venules are throughout the endometrium.

Myometrium (muscularis).

Note the thickness of the myometrium and the density of the muscle. Attempt to define the three layers of muscle but in a section it is difficult to do so.

Stratum subvasculare, adjacent to the endometrium. Muscle fibers are in compact bundles, in cross or oblique sections (course longitudinally in the intact uterus), with prominent septa between them.

Stratum vasculare, the middle layer, the thickest part of the muscularis. Interlacing bundles of muscle course both circularly and spirally.

Note the large blood vessels in the deeper part of this stratum. Their peculiarities are normal for the uterus. These include muscle in the intima of the arteries, increased muscle in the media of the veins, and sometimes muscle in the adventitia of both. (Some arteries in this slide have arteriosclerosis or intimal hyalinzation.)

Stratum supravasculare, the thin most peripheral layer, with longitudinal and circular fibers.

Perimetrium (typical serosa): mesothelium and a little underlying loose connective tissue.

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=== Slide 261, Uterus (H&E) ===

Slide 261, Uterus (H&E), later proliferative phase, probably about days 10-12.

Study the endometrium in comparison with slide 278.

Note that the endometrium is a wider layer.

Stroma is much less compact - more tissue fluid is present, fibroblasts are farther apart. Nearer the epithelium, stroma in places is beginning to have a spongy appearance.

Glandular cells are larger, nuclei are large and vesicular, and epithelium appears pseudostratified. Secretion (glycogen, mucin) is beginning to accumulate at the bases of many cells. Small vacuolated areas represent the secretions that are removed during section preparation.

Fibroblasts are seen more distinctly in the looser stroma; note their processes. Look for mitoses. Small lymphocytes are scattered throughout.

Look for coiled arteries but they are not too prominent on this slide. Look for other small blood vessels.

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=== Slide 262, Uterus (H&E) ===

Slide 262, Uterus, (H&E) exhibits endometrium in a very late secretory phase or early premenstrual (probably days 24-26 of cycle; it is difficult to date precisely).

Study the endometrium of this phase of the uterine cycle.

Compare the width of the endometrium in this phase of the cycle with that in the previous slide.

Note the characteristic large sacculated glands (“corkscrew appearance”). These are prominent throughout most of the functional zone. In the upper region of the functionalis zone (towards the surface) the glands have larger lumina but the sacculations in the walls are less.

Note the position of the nuclei and the size of the glandular cells. Secretory material has moved from the infranuclear position to the supranuclear position, and some secretion has been liberated into the lumens of the glands. Therefore, the cells are smaller than in the earlier secretory stages, pseudostratification is much less apparent, and nuclei are basally located.

Note areas of edema in the functional zone, but much of the excessive tissue fluid has already been resorbed.

Note now the large size of the coiled arteries and their extent halfway or more upward into the functional zone.

Observe the increased vascularity of capillaries and venules, especially in the outer functional zone. Some may already have ruptured.

The surface epithelium is still intact.

Note the myometrium and its blood vessels. Perimetrium is not present.

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=== Slide 281, Cervix and OS Cervix, one wall (H&E) ===

Slide shows endocervical epithelium and glands. The plane of section missed the junctional zone between endocervix and os cervix.

Locate the os cervix (portio vaginalis) which is lined with stratified squamous epithelium. It can be seen grossly on the right margin of the section.

Look along either surface of the section for cervical mucosa. The simple columnar lining epithelium consists of tall columnar cells, mucus-secreting; the luminal margin of the cells often appears indistinct or ragged. Note the Nabothian cyst (a cyst of a mucous gland of the cervix).

The surface epithelium continues down to line the simple branched tubular mucus-secreting cervical glands.

The lamina propria is no longer a primitive connective tissue as in the uterine endometrium.

The mucosa is often folded, forming plicae palmatae.

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== Vagina ==

The vagina is a thick-walled fibromuscular tube that connects the uterus with the exterior and serves as a cavity for the reception of the penis at coitus and as a birth canal at the time of parturition.

=== Slide 266, Vagina (H&E) ===

The wall of the vagina consists of a mucosa, a muscularis, and a broad fibrosa that connects it to adjacent structures. The mucosa is thrown into broad folds (rugae) which are gross structures, not demonstrable in a small piece of tissue used for microscopic slides.

Mucosa

The epithelium is non-cornified stratified squamous. Note the stratum basale, the stratum spinosum, and the stratum corneum, so-called even though it is not cornified. The cells that appear empty contain glycogen and mucin, both of which are removed during routine section preparation.

The broad areas of epithelium are tangential sections. Cross-sections of connective tissue papillae may be seen within them.

Note connective tissue papillae projecting into the epithelium from the lamina propria. These are characteristic of most stratified squamous epithelia.

The lamina propria is a broad zone of highly vascularized connective tissue, with abundant elastic fibers, extending to the muscularis. The elastic fibers may be seen as fine homogenous threads. (There is no muscularis mucosae or submucosa.) Note numerous small blood vessels and nerves. In many of the vessels, the endothelial cells (nuclei) are hypertrophied - not a normal condition.

Scattered lymphocytes and plasma cells are seen throughout the mucosa. Lymphocytes may aggregate just below the epithelium to form diffuse lymphatic tissue or an occasional small nodule. Lymphocytes may penetrate the epithelium to migrate toward its surface.

The muscularis, mostly arranged longitudinally, appears as bundles of smooth muscle interspersed with connective tissue rich in elastic fibers which may be seen as thin, homogenous threads. Larger blood vessels, as well as small ones, are found in the deep muscularis or fibrosa.

The fibrosa is loose connective tissue. It should have some adipose tissue and nerves.

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=== Slide 265, Vagina (Masson) ===

Identify the regions of the wall and their component parts as in slide 266.

Muscle and connective tissue are easily differentiated with Masson’s; they stain red and blue respectively. All nuclei stain red, as do erythrocytes. Elastic fibers are not distinguishable.

The vascularity of the lamina propria is emphasized, with many of the venules congested.

The large amount of connective tissue between the muscle bundles is well demonstrated.

Lightly staining nerves occur among the muscle bundles and in the fibrosa.

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== Placenta and Umbilical Cord ==

Slides: 275, 264, 273, 274, 279, 280.

=== Slide 275, Chorionic Villi (H&E) ===

This is a section of a small part of a fetal placenta of a very early pregnancy, showing chorionic villi and the surrounding maternal blood spaces. Some slides have a strip of chorionic plate across the upper margin of the section.

Chorionic plate

The greater part of the plate is chorion, composed of a mass of embryonic connective tissue (large fibroblasts, fine collagenous fibers, abundant ground substance), covered on its lower surface by a double layer of epithelial cells: the cytotrophoblast adjacent to the connective tissue, and the syntrophoblast (syncytial trophoblast) on the free surface, bordering on maternal blood spaces.

Cells of the syntrophoblast do not show cell boundaries. Ragged cell surfaces indicate microvilli. Cells of the cytotrophoblast supposedly show cell boundaries but they are not readily seen here. They divide to form syntrophoblast.

Note blood vessels in the connective tissue (branches of umbilical vessels) containing nucleated fetal red blood corpuscles.

The small zone of looser connective tissue in the upper part of the chorionic plate is part of the amnion. The cuboidal surface epithelium has been torn off.

Chorionic villi. The villi are outgrowths from the chorion, having the same structure as the chorion. They increase in size and branch repeatedly as they invade the maternal blood spaces. The initial larger villi will become the anchoring villi that will penetrate the endometrium (decidua basalis) to anchor the fetal placenta. Smaller villi sprout off the anchoring villi.

Note that the villi vary in size. The largest ones are potential anchoring villi. Others are floating villi; their free ends are in the blood spaces.

Each villus has a core of embryonic connective tissue, branches of umbilical vessels (sparse in this early placenta), and a covering of inner cytotrophoblast and superficial syntrophoblast.

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=== Slide 264, Uterus and Placenta from a later stage of pregnancy (PASH) ===

Look at the fetal placenta.

Villi are larger and more numerous than in slide 275, stroma is generally more compact with more collagenous fibers (still fine) and abundant fibroblasts.

Blood vessels in the villi are more numerous. Capillaries and little venules are peripherally located close to the trophoblast cells, although this may not be obvious due to plane of sections. Note that now red blood corpuscles are not nucleated.

Syntrophoblast and cytotrophoblast are still present but cytotrophoblast is incomplete in many areas. (It will disappear entirely by late pregnancy.)

Look for macrophages (Hofbauer cells) in the stroma of the villi - large rounded cells whose cytoplasm may have small vacuoles and/or PAS positive granules.

Look for syncytial knots on the surface of villi or in the intervillous spaces. These are groups of syntrophoblast cells that detach from the villi and float freely in the spaces; progressively more are formed toward term.

Look for very small deposits of fibrinoid, on or in the villi or in the intervillous spaces, a non-cellular, homogenous, proteinaceous material associated with transplantation immunity to protect the fetus.

Maternal placenta (decidua basalis) and uterus. The decidua basalis is the name given to the endometrium that underlies the villi of the fetal placenta. Some villi (anchoring villi) penetrate the decidua basalis (endometrium) for varying distances. In doing so, part of the surface of the endometrium has been eroded and destroyed (surface epithelium is missing).

Look for anchoring villi attaching to the decidua basalis. Note larger fibrinoid deposits and aggregations of syncytial knots in this region.

In the decidua basalis, note the vast numbers of large and smaller decidual cells with PAS- positive cytoplasm (are storing glycogen) and large, lightly staining nuclei. Cytoplasm of those with less glycogen stains faintly acidophilic or somewhat grayish. Decidual cells are derived from fibroblasts of the endometrium.

A few glands are seen in the basal zone of the endometrium. They may be dilated, have very low epithelium or hypertrophied epithelium, and have lymphocytic infiltration surrounding some of them.

Identify the myometrium and note the large size of the muscle fibers that hypertrophy greatly during pregnancy.

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=== Slide 280. Uterus and Placenta near term (H&E) ===

Fetal placenta. Proliferation of villi has continued to increase during pregnancy.

Note the great number of chorionic villi, practically filling the maternal blood spaces. The anchoring villi have become very large. The connective tissue in the core is fibrous, but embryonic connective tissue has persisted at the periphery. The larger blood vessels course in these villi. Observe the variation in size of the floating villi, which continue to form throughout pregnancy.

In the villi, note further compactness of stroma, areas of more dense collagenous fibers, more capillaries, and venules close to the trophoblast.

Look for macrophages (Hofbauer cells) in the stroma of the villi. With H&E, the cytoplasm is finely vacuolated.

Syntrophoblasts still cover the surface of the villi. Cytotrophoblasts have generally disappeared.

Note increased number of syncytial knots and much fibrinoid material. Knots are seen deep in the endometrium; they appear as darkly stained groups of pyknotic nuclei.

The maternal placenta (decidua basalis).

Again note the placental villi anchoring into the endometrium.

Decidual cells are still present in the endometrium but many have “used up” their glycogen and are reverting to fibroblasts. Lymphocytic infiltration is seen in places. Much fibrinoid is present.

Uterine glands, whose basal portions had remained inactive, are proliferating and regenerating. Some appear cystic.

Uterine Muscularis.

The three layers are not readily identified, but note again the large size of the fibers.

Note the huge multinucleated giant cells in the deep endometrium and especially in the muscularis. They are thought to be of trophoblastic origin (perhaps differentiated from but not to be confused with syncytial knots).

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=== Slide 279. Placenta at term (H&E) ===

These slides are from a “fresh” placenta immediately after parturition; thus very little postmortem change is present and structures are seen distinctly.

Go over the fetal placenta as in slide 280. Numerous red blood corpuscles are present in the maternal blood spaces, probably due to rupture of blood vessels during parturition.

Note the tremendous vascularity of the placental villi, apparent here because of the fresh condition of the tissues; note also the great number of syncytial knots.

A fragment of decidua basalis may be present (left end of the section in the field). Anchoring villi are seen and large decidual cells may still be present.

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=== Slide 274, Placenta at term (PASH) ===

This tissue is from the same placenta used for making slides 279 and 273. Look at the slide to see how term structures stain with PASH.

Basement membranes are prominent under the syntrophoblast and under endothelium of the blood vessels. Note also that blood vessels are more numerous in these villi than in those of slide 280, are also congested which may be the cause of their large size.

Areas of decidua basalis are present.

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=== Slide 273, Placenta, term (Masson) ===

This tissue is from the same placenta as used for making slides 274 and 279.

Identify the structures as seen with this stain. Connective tissue elements are blue, nuclei are reddish or indistinct, and the cytoplasm varies.

This section shows the chorionic plate at the right (in the field).

The outer “membrane” is the amnion, consisting of a layer of cuboidal or low columnar epithelium and a thin layer of connective tissue. It is mechanically separated from the underlying chorion.

The chorion consists of a layer of connective tissue covered by syncytial trophoblast that is now mostly fibrinoid.

Two main umbilical vessels and smaller branches are passing through the chorionic plate.

<peir-vm>UAB-Histology-00273</peir-vm>

== Umbilical Cord ==

=== Slide 287, Umbilical Cords (H&E) ===

Slide 287, Umbilical Cords (H&E), is from an early pregnancy and from late in pregnancy.

The early pregnancy umbilical cord is on the left. The two umbilical arteries and the umbilical vein look generally similar because of the atypical large amount of muscle in the wall. An internal elastic membrane is lacking in the arteries. The diameter of the vein is greater than that of the artery and the muscle is not quite as compactly arranged.

The stroma of the cord is mucous connective tissue - embryonic connective tissue with a mucoid ground substance (Wharton’s jelly) which is removed in section preparation. Note the fine collagenous fibers and the large branched fibroblasts.

Covering the cord is simple squamous or simple cuboidal epithelium, part of the amnion.

<peir-vm>UAB-Histology-00287</peir-vm>

=== Slides 287 (tissue on right) and Slide 277, umbilical cord at term (H&E) ===

In this fully developed placenta, the atypical structure of the arteries is well shown - a wide inner layer of longitudinally arranged muscle and a thick outer circular layer. Postmortem contraction causes collapse of the vessels. The vein has some inner longitudinal muscle; most of it is outer circular. Reticular fibers between muscle fibers are seen with H&E (due to postmortem shrinkage of muscle fibers). The small vacuoles are probably early degenerative changes.

Collagenous fibers in the stroma are somewhat heavier than in the earlier cord but are not mature fibers. Mucous connective tissue retains its embryonic nature; note that fibroblasts are still large branched cells.

Neutrophils are invading some areas of the stroma (lower field especially), also related to breakdown of the tissues.

Epithelium of the amnion surrounds the cord.

==== Slide 287, Umbilical Cord at term (tissue on right) (H&E) ====
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==== Slide 277, Umbilical Cord at term (H&E) ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 6

2014-07-10T21:04:53Z

Seung Park: /* Spinal Cord - General Structure */

== Introduction ==
[[File:HistologicChapter6Neurons.jpg|thumb|200px|Neurons]]
Nervous tissue is highly specialized to form the nervous system which is organized into two major divisions: The central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of all the nervous tissue lying outside of the brain and the spinal cord. This is subdivided into the cerebrospinal portion (the 12 pairs of cranial nerves, 31 pairs of spinal nerves and associated ganglia) and the autonomic nervous system (sympathetic and parasympathetic components) which deals with visceral activities (smooth muscle, cardiac muscle, and glandular secretions). These parts of the nervous system are not separate entities but are structurally and functionally interdependent. The nerves of the peripheral nervous system are widely distributed throughout the body, extending into all tissues and organs.

The structural and functional unit of the nervous system is the neuron, which is defined as a nerve cell body and all of its processes. Nerve cell bodies are located with the CNS and in the various ganglia outside of the CNS. The processes are dendrites and axons. Neurons function in cooperating groups or chains, some receiving the excitation and passing it on to others, often in many relays, until somewhere in the body a response is affected. Structurally, neurons are classified as multipolar, bipolar, and unipolar according to the number of processes arising from the cell body.

A nerve is a collection or aggregation of nerve fibers outside the CNS, surrounded by a sheath of connective tissue and supported by connective tissue stroma. A nerve fiber consists of an axonal process enveloped with one or two sheaths (myelin sheath and/or neurolemma or Schwann’s sheath).

A ganglion is a group of nerve cell bodies located outside of the central nervous system. These are termed: cranial ganglia, dorsal root ganglia, sympathetic ganglia, and parasympathetic ganglia.

== Nerve Fibers And Nerves ==

=== Slide 27: Peripheral Nerve (Osmium), Cross and Longitudinal Sections ===

Osmium stains myelin, therefore the myelin sheaths will be black, unmyelinated fibers are vaguely outlined, other structures do not stain.

These are sections of a typical peripheral nerve, which contains myelinated fibers of various sizes as well as unmyelinated fibers. Note--axons always shrink in routinely prepared sections.

Look first at the cross section.

Note the epineurium surrounding the entire nerve and sending extensions between the fasciculi (interfascicular CONNECTIVE TISSUE).

Note perineurium surrounding each large fasciculus of nerve fibers. The “cracks” or spaces in some of the fasciculi were sites of smaller perineurial septa.

Within each fasciculus, note myelinated nerve fibers of different sizes. The axon may be faintly apparent (shrunken) or completely unstained.

Focus carefully to see very small thinly myelinated fibers. Unmyelinated fibers are virtually impossible to distinguish.

Look at the longitudinal section

Identify the same structures as above, also fat cells stained with osmium, in the epineurium.

In good longitudinal sections of the larger fibers look for the nodes of Ranvier, but they are not easily seen because of tissue contraction.

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=== Slide 50: Peripheral Nerve (Masson’s Stain) ===

Connective tissue stains blue, nuclei are dark blue, and myelin is orange-red.

Repeat the study of the cross and longitudinal sections as for slide 27 but now detailed structure can be seen. The perineurium should stain blue, but it may be partially red, probably because of inability of the blue stain to completely penetrate this dense tissue.

Note especially that perineurial septa and endoneurium are seen distinctly. The nuclei that appear to be in the endoneurium are fibroblast nuclei of the endoneurium and neurolemma cell (Schwann cell) nuclei; do not try to distinguish between them, but the majority are neurolemma (Schwann) nuclei.

In the nerve fibers, the axon may or may not be stained. Myelin is partly removed from the myelin sheath, leaving the neurokeratin network.

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=== Slide 13: Peripheral Nerve (H&E) ===

Check the same features as previously described, in this cross-section, to see their appearance with a routine stain.

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== Central Nervous System: Brain ==
[[File:HistologicChapter6Brain.jpg|thumb|200px|Brain: Meninges]]
The central nervous system (CNS) comprises the brain and spinal cord. These areas contain nerve cells and their processes, along with specialized support cells.

The specialized support cells of the CNS are collectively called glia. These are astrocytes, oligodendrocytes, ependyma and microglial cells. Astrocytes are stellate cells that are involved in fluid transport and structural support. The stellate morphology is not evident in conventional H&E sections because the processes merge with the processes of other cells, but is seen with special staining methods. Two types of astrocyte have been identiﬁed. Fibrous astrocytes are most evident in the white matter and have long cell processes which are rich in bundles of glial ﬁbrillary acidic protein (GFAP). Protoplasmic astrocytes are most evident in the gray matter of the brain and have long thin processes containing few bundles of GFAP.

One important structural adaptation of astrocytes is seen in their interaction with the blood vessels of the brain, which they surround by forming flat plates termed end feet. The interaction induces changes in the structure of the cerebral vascular endothelium, rendering it highly impermeable, so that it acts as a barrier to diffusion between the blood and the brain, the “blood-brain-barrier”.

Oligodendrocytes are the myelin-producing cells of the CNS, each cell sending out several cell processes and myelinating several nearby axons. In routine histologic sections their branching morphology is not seen, but they do show a rounded nucleus with moderately dense-staining chromatin and, in most preparations, a cytoplasm containing a clear ‘halo’ around the nucleus. Such a halo is an artifact of preparation because oligodendrocytes are fragile and contain few cytoskeletal elements.

Ependymal cells are epithelial like cells that line the cavities in the brain (ventricles) and the central canal of the spinal cord, forming a sheet of cuboidal cells in contact with the cerebrospinal fluid. Each ependymal cell has a small oval basal nucleus with dense chromatin, and many are ciliated. Unlike other epithelial cells, the ependymal cells do not lie on a basement membrane but have tapering processes which merge with the processes of underlying astrocytic cells.

The CNS has its own unique set of immune cells, the main type being the microglial cells, which are specialized macrophages. In conventional H&E preparations microglial cells are not easily seen, appearing only as rod-shaped nuclei with no discernible cytoplasmic borders. The phenotype of microglia suggests that they are similar to dendritic antigen-presenting cells, having a low level of phagocytic activity and expressing class II major histocompatibility molecules.

In disease states microglial cells become activated and increase in size and number. Under these circumstances they are usually supplemented by monocytes, which enter the brain from the blood and form macrophagic cells. The brain appears to have only a very small traffic of lymphoid cells in the normal state.

The CNS has three protective coats, the meninges, which are composed of ﬁbrocollagenous support tissue and epithelial cells. These three layers are: the dura, the arachnoid and the pia.

The dura is a tough ﬁbrocollagenous layer, which forms the outer coat of the CNS. It blends with the periosteum of the skull and is attached to the periosteum of the vertebral canal by the dentate ligaments. It is covered on its internal surface by an incomplete layer of flat epithelial cells. The dura is reflected down from the skull to form sheets of tissue, the tentorium cerebelli and the falx cerebri, which separate the structures of the brain. The venous sinuses of the brain run at the base of these sheets of dura.
The arachnoid is a layer of ﬁbrocollagenous tissue covered by inconspicuous flat epithelial cells and is located beneath, but not anchored to, the dura. Web-like strands of ﬁbrocollagenous tissue extend down from the arachnoid into the subarachnoid space, which contains the cerebrospinal fluid. The main arteries and veins to and from the brain run in the subarachnoid space.

The pia is a delicate layer of epithelial cells associated with loose ﬁbrocollagenous tissue. It lies external to a basement membrane which completely surrounds the CNS.

=== Slide 72: Cerebral Cortex (H&E) ===

With H&E, the meninges as well as the various layers of the cerebral cortex are visible. Distinguish the general regions of the cerebral cortex:

*White matter.
**Note few cells per unit area. Cells in the white matter are microglia with few if any neuron bodies.
*Gray matter (cerebral cortex).
**The cerebral cortex is divided into six layers. Distinguishing the exact borders of these layers is difficult requiring special staining and is beyond the scope of this discussion. The six layers from outside to inside include: plexiform or molecular layer, small pyramidal cell layer, medium pyramidal cell layer, granular layer, large pyramidal cell layer, and the polymorphic cell layer.
*Meninges consisting of the pia mater.

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=== Slide 14: Cerebellum (H&E) ===

The outer portion of the cerebellum, the cortex, is made up of a molecular layer and a granular layer. At the junction between these two layers are the large cell bodies of Purkinje cells. These cells are characteristic of cerebellum. They contain numerous dendrites that extend into the molecular layer and a single axon.

The central portion of the cerebellum consists of myelinated fibers which make up the white matter.

The choroid plexuses are located in the ventricular system of the brain and produce cerebrospinal fluid. Each choroid plexus consists of a vascular stroma covered by columnar epithelial cells, which form large frond-like masses. The cerebrospinal fluid produced in the ventricles flows out through exit foramina at the base of the brain and circulates in the subarachnoid space. It is reabsorbed by the venous sinuses in the dura.

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=== Slide 15: Choroid plexus (Masson) ===
[[File:HistologicChapter6BrainSagittalSectionLabeled.jpg|thumb|200px|Brain Sagittal Section Labeled]]
On this trichrome stained section of choroid plexus note the multiple fronds of tissue. Each is covered with ependymal cells and has a connective tissue infrastructure.

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== Spinal Cord: General Structure ==
[[File:HistologicChapter6SpinalCord.jpg|thumb|200px|Spinal Cord]]
The spinal cord is composed of two principal parts extending the length of the cord, the inner core of gray matter and an outer layer of white matter. The entire cord is supported in a framework of neuroglia. In the most peripheral part of the cord, processes of fibrous astrocytes condense to form the marginal glial membrane, in which nerve fibers are absent.

The gray matter is in the form of two large lateral masses connected by a narrow strip across the midline, the gray commissure, in which lies the central canal, which is largely obliterated in the adult. Each lateral gray mass has a dorsal gray horn or column, a ventral gray horn or column, and an intermediate gray area. The configuration of the gray matter varies in different parts of the cord; the ventral horns are widest in the cervical and lumbar enlargements in which are located the anterior horn cells that innervate the upper and lower extremities respectively, and narrowest in the thoracic segments.

All neuron cell bodies, together with their dendrites and initial portions of their dendrites and initial portions of their axons, are in the gray matter. Unmyelinated nerve fibers course everywhere as well as some myelinated fibers (terminations of incoming sensory fibers or tract fibers in the white matter). Blood vessels are prevalent.

The white matter is composed of nerve fibers, most of which are myelinated, connective tissue septa with blood vessels coming in from the pia matter, and neuroglia septa. Dorsal roots (incoming sensory fibers) are attached to the dorsal lateral surface of the cord (dorsolateral sulcus), and ventral roots to the ventrolateral surface (ventrolateral sulcus). In relation to these, the white matter is divided into the dorsal white columns, lateral white columns, and ventral white columns. Ventrally, there is a deep medial ventral fissure, and dorsally a shallow medial sulcus.
The cord is covered with meninges consisting of the outermost thick fibrous dura mater, a subdural space, the arachnoid and subarachnoid space with arachnoid trabeculae which contains cerebrospinal fluid, and the pia mater, a fibrous membrane attached to the spinal cord. The latter two membranes are often referred to as the pia-arachnoid. From the pia mater, connective tissue septa carrying blood vessels penetrate the white and gray matter.

When dorsal root fibers enter the cord and ventral root fibers first leave the cord, they lie in the subarachnoid space. As they move laterally to exit through the intervertebral foramina, the dura mater continues over them as epineurium. The arachnoid fades out quickly.

=== Slide 97: Lumbar Cord With Meninges, Three-Year Old Child (H&E) ===

With H&E, details of neuron cell bodies are seen quite well; other tissues stain much as in other organs.

Distinguish the general regions of the cord:
*The H-shaped gray matter with its dorsal gray columns, the broad ventral columns, and the intermediate gray area.
*The white matter with its three divisions.
*The delicate dorsal medial (posterior) septum of neuroglia and the ventral fissure.
*The thick dura mater (dense fibrous connective tissue) - the outermost layer of the meninges.
*The central canal in the gray commissure. It is lined with ependymal cells, which have a columnar shape; some may have flagella.

White matter.

*Note innumerable myelinated fibers, mostly in cross sections, since these are mainly ascending and descending tracts. Myelin is not preserved; a clear space remains. The axon is unstained or faintly seen, or it may not be present.
*Thin connective tissue septa and small blood vessels can be seen. Look for perivascular spaces around the blood vessels - clear spaces that are actinically enlarged due to shrinkage of tissues.
*The numerous small nuclei seen are mainly those of fibrous astrocytes and oligodendroglia.
*Identify the marginal glial membrane. It forms the most peripheral part of the spinal cord, is formed by processes of fibrous astrocytes, and lacks nerve fibers.

Dorsal gray columns.

*Note the uppermost large pale area (substantia gelatinosa), the more fibrillar base of the dorsal horn, and myelinated fibers sweeping into these areas from the dorsal white columns (incoming sensory fibers).
*The small nuclei are astrocyte and oligodendroglia nuclei. Small neuron cell bodies are not easily seen.
*Some of the sections may show the actual entrance of the dorsal roots.

Ventral gray columns - general. The columns are broad.

Note the meshwork of fine fibers throughout (unmyelinated nerve fibers, processes of astrocytes), nuclei of astrocytes and oligodendrocytes, small blood vessels in their perivascular spaces, and large anterior horn cells.

The anterior horn cells (Motor Neurons)

*In sections, entire cells are rarely seen, but note the multipolar shapes of the cells, parts of cell processes, Nissl bodies, in the neuroplasm and the distinctive nucleus and nucleolus. Dendrites are short processes that contain Nissl bodies. Look for a cell that shows a clear axon hillock and an emerging axon.

*Note the perineuronal space (exaggerated in sections) around each cell body with occasional perineuronal satellite cells close to the cell body. Satellite cells are astrocytes and/or oligodendrocytes.

*Axons of these anterior horn cells can be seen in groups passing down into the ventral white matter to emerge to form the ventral roots. They innervate the muscles of the lower extremities.

*Innumerable nuclei of neuroglia cells are seen everywhere throughout the gray matter; their cytoplasmic processes shrink to invisibility. Identify astrocytes and oligodendrocytes.

Astrocytes have rounded, somewhat lightly-staining (vesicular) nuclei; they vary in size.

Oligodendrocytes have small, darker-stained nuclei, much like a miniature lymphocyte.

Microglia are not as numerous nor as easily identified (do NOT try to identify them). Microglia are phagocytic cells derived from monocytes.

Look for very small internuncial (connector) neurons scattered throughout the ventral gray. They are typical, but small, neurons. These are interposed between sensory and motor neurons in reflex pathways.

Meninges of the spinal cord.

*Distinguish the pia mater of fibrous connective tissue immediately around the cord.

*In the subarachnoid space, note bundles (fasciculi) of nerve fibers - rootlets of dorsal and ventral roots.

*Distinguish the arachnoid membrane (if not torn) forming the peripheral boundary of the space - a thin connective tissue membrane covered with a layer of squamous cells. It sends fine trabeculae across the space.

*The dense fibrous dura mater lies external to the arachnoid. A subdural space lies between the dura and arachnoid.

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== Sympathetic Chain Ganglion With Multipolar Neurons ==

These are the post-ganglionic visceral efferent neurons. Axons of neurons in the lateral sympathetic nucleus of the thoracic cord had come to the sympathetic chain via the white rami communicantes. Many have synapsed on these ganglion cells. (Others pass through the chain to synapse elsewhere.)

=== Slide 16: Sympathetic Ganglion (H&E) ===

This ganglion has an epineurium but many ganglia do not show such a distinct capsule.

The ganglion cells are more loosely arranged than in the spinal ganglion. Connective tissue stroma is more apparent, also septa with blood vessels.

Ganglion cells are more uniform in size. All are multipolar.

Note typical characteristics of neuron cell bodies: nuclei may be eccentrically placed, an occasional cell is binucleated, and a few cells have yellow pigment. These are normal features of sympathetic ganglion cells.

Perineuronal spaces are less constant, satellite and capsule cells are more variable in number but are present.

Nerve fibers in the stroma are largely unmyelinated or finely myelinated, and less easily identified with routine stains.

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== Parasympathetic Ganglia ==

These are in the walls of organs. Preganglionic parasympathetic fibers go from the cell bodies in the brain stem or sacral spinal cord to the organs to be innervated and synapse on small, typical multipolar neuron cell bodies in ganglia (post-ganglionic neurons). Postganglionic fibers (axons) of these are then distributed to smooth muscle and glands.

=== Slide 94: Colon (H&E) ===

Between the two muscle layers of the esophagus and all subsequent parts of the digestive tract, is a chain of parasympathetic ganglia and vagus nerve fibers (myenteric plexus of Auerbach). The fibers are finely myelinated or unmyelinated. Groups of ganglion cells are seen intermittently within the chain. Look for lightly stained areas between the muscle layers and note:

Small nerves surrounded by a thin perineurium. The numerous nuclei within the nerve are nuclei of neurolemma cells (Schwann cells) or fibroblasts of the endoneurium.

Varying numbers of multipolar ganglion cells (only parts of cells may be seen).

Look for a complete cell that shows the characteristic nucleus and nucleolus. Nuclei may be eccentrically located.

Perineuronal spaces, capsule cells, and satellite cells are present but not as consistent as in the large dorsal root ganglion cells.

The interstitial material is unmyelinated nerve fibers and endoneurium.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 6

2014-07-10T21:02:50Z

Seung Park: /* Slide 72: Cerebral Cortex (H&E) */

== Introduction ==
[[File:HistologicChapter6Neurons.jpg|thumb|200px|Neurons]]
Nervous tissue is highly specialized to form the nervous system which is organized into two major divisions: The central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of all the nervous tissue lying outside of the brain and the spinal cord. This is subdivided into the cerebrospinal portion (the 12 pairs of cranial nerves, 31 pairs of spinal nerves and associated ganglia) and the autonomic nervous system (sympathetic and parasympathetic components) which deals with visceral activities (smooth muscle, cardiac muscle, and glandular secretions). These parts of the nervous system are not separate entities but are structurally and functionally interdependent. The nerves of the peripheral nervous system are widely distributed throughout the body, extending into all tissues and organs.

The structural and functional unit of the nervous system is the neuron, which is defined as a nerve cell body and all of its processes. Nerve cell bodies are located with the CNS and in the various ganglia outside of the CNS. The processes are dendrites and axons. Neurons function in cooperating groups or chains, some receiving the excitation and passing it on to others, often in many relays, until somewhere in the body a response is affected. Structurally, neurons are classified as multipolar, bipolar, and unipolar according to the number of processes arising from the cell body.

A nerve is a collection or aggregation of nerve fibers outside the CNS, surrounded by a sheath of connective tissue and supported by connective tissue stroma. A nerve fiber consists of an axonal process enveloped with one or two sheaths (myelin sheath and/or neurolemma or Schwann’s sheath).

A ganglion is a group of nerve cell bodies located outside of the central nervous system. These are termed: cranial ganglia, dorsal root ganglia, sympathetic ganglia, and parasympathetic ganglia.

== Nerve Fibers And Nerves ==

=== Slide 27: Peripheral Nerve (Osmium), Cross and Longitudinal Sections ===

Osmium stains myelin, therefore the myelin sheaths will be black, unmyelinated fibers are vaguely outlined, other structures do not stain.

These are sections of a typical peripheral nerve, which contains myelinated fibers of various sizes as well as unmyelinated fibers. Note--axons always shrink in routinely prepared sections.

Look first at the cross section.

Note the epineurium surrounding the entire nerve and sending extensions between the fasciculi (interfascicular CONNECTIVE TISSUE).

Note perineurium surrounding each large fasciculus of nerve fibers. The “cracks” or spaces in some of the fasciculi were sites of smaller perineurial septa.

Within each fasciculus, note myelinated nerve fibers of different sizes. The axon may be faintly apparent (shrunken) or completely unstained.

Focus carefully to see very small thinly myelinated fibers. Unmyelinated fibers are virtually impossible to distinguish.

Look at the longitudinal section

Identify the same structures as above, also fat cells stained with osmium, in the epineurium.

In good longitudinal sections of the larger fibers look for the nodes of Ranvier, but they are not easily seen because of tissue contraction.

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=== Slide 50: Peripheral Nerve (Masson’s Stain) ===

Connective tissue stains blue, nuclei are dark blue, and myelin is orange-red.

Repeat the study of the cross and longitudinal sections as for slide 27 but now detailed structure can be seen. The perineurium should stain blue, but it may be partially red, probably because of inability of the blue stain to completely penetrate this dense tissue.

Note especially that perineurial septa and endoneurium are seen distinctly. The nuclei that appear to be in the endoneurium are fibroblast nuclei of the endoneurium and neurolemma cell (Schwann cell) nuclei; do not try to distinguish between them, but the majority are neurolemma (Schwann) nuclei.

In the nerve fibers, the axon may or may not be stained. Myelin is partly removed from the myelin sheath, leaving the neurokeratin network.

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=== Slide 13: Peripheral Nerve (H&E) ===

Check the same features as previously described, in this cross-section, to see their appearance with a routine stain.

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== Central Nervous System: Brain ==
[[File:HistologicChapter6Brain.jpg|thumb|200px|Brain: Meninges]]
The central nervous system (CNS) comprises the brain and spinal cord. These areas contain nerve cells and their processes, along with specialized support cells.

The specialized support cells of the CNS are collectively called glia. These are astrocytes, oligodendrocytes, ependyma and microglial cells. Astrocytes are stellate cells that are involved in fluid transport and structural support. The stellate morphology is not evident in conventional H&E sections because the processes merge with the processes of other cells, but is seen with special staining methods. Two types of astrocyte have been identiﬁed. Fibrous astrocytes are most evident in the white matter and have long cell processes which are rich in bundles of glial ﬁbrillary acidic protein (GFAP). Protoplasmic astrocytes are most evident in the gray matter of the brain and have long thin processes containing few bundles of GFAP.

One important structural adaptation of astrocytes is seen in their interaction with the blood vessels of the brain, which they surround by forming flat plates termed end feet. The interaction induces changes in the structure of the cerebral vascular endothelium, rendering it highly impermeable, so that it acts as a barrier to diffusion between the blood and the brain, the “blood-brain-barrier”.

Oligodendrocytes are the myelin-producing cells of the CNS, each cell sending out several cell processes and myelinating several nearby axons. In routine histologic sections their branching morphology is not seen, but they do show a rounded nucleus with moderately dense-staining chromatin and, in most preparations, a cytoplasm containing a clear ‘halo’ around the nucleus. Such a halo is an artifact of preparation because oligodendrocytes are fragile and contain few cytoskeletal elements.

Ependymal cells are epithelial like cells that line the cavities in the brain (ventricles) and the central canal of the spinal cord, forming a sheet of cuboidal cells in contact with the cerebrospinal fluid. Each ependymal cell has a small oval basal nucleus with dense chromatin, and many are ciliated. Unlike other epithelial cells, the ependymal cells do not lie on a basement membrane but have tapering processes which merge with the processes of underlying astrocytic cells.

The CNS has its own unique set of immune cells, the main type being the microglial cells, which are specialized macrophages. In conventional H&E preparations microglial cells are not easily seen, appearing only as rod-shaped nuclei with no discernible cytoplasmic borders. The phenotype of microglia suggests that they are similar to dendritic antigen-presenting cells, having a low level of phagocytic activity and expressing class II major histocompatibility molecules.

In disease states microglial cells become activated and increase in size and number. Under these circumstances they are usually supplemented by monocytes, which enter the brain from the blood and form macrophagic cells. The brain appears to have only a very small traffic of lymphoid cells in the normal state.

The CNS has three protective coats, the meninges, which are composed of ﬁbrocollagenous support tissue and epithelial cells. These three layers are: the dura, the arachnoid and the pia.

The dura is a tough ﬁbrocollagenous layer, which forms the outer coat of the CNS. It blends with the periosteum of the skull and is attached to the periosteum of the vertebral canal by the dentate ligaments. It is covered on its internal surface by an incomplete layer of flat epithelial cells. The dura is reflected down from the skull to form sheets of tissue, the tentorium cerebelli and the falx cerebri, which separate the structures of the brain. The venous sinuses of the brain run at the base of these sheets of dura.
The arachnoid is a layer of ﬁbrocollagenous tissue covered by inconspicuous flat epithelial cells and is located beneath, but not anchored to, the dura. Web-like strands of ﬁbrocollagenous tissue extend down from the arachnoid into the subarachnoid space, which contains the cerebrospinal fluid. The main arteries and veins to and from the brain run in the subarachnoid space.

The pia is a delicate layer of epithelial cells associated with loose ﬁbrocollagenous tissue. It lies external to a basement membrane which completely surrounds the CNS.

=== Slide 72: Cerebral Cortex (H&E) ===

With H&E, the meninges as well as the various layers of the cerebral cortex are visible. Distinguish the general regions of the cerebral cortex:

*White matter.
**Note few cells per unit area. Cells in the white matter are microglia with few if any neuron bodies.
*Gray matter (cerebral cortex).
**The cerebral cortex is divided into six layers. Distinguishing the exact borders of these layers is difficult requiring special staining and is beyond the scope of this discussion. The six layers from outside to inside include: plexiform or molecular layer, small pyramidal cell layer, medium pyramidal cell layer, granular layer, large pyramidal cell layer, and the polymorphic cell layer.
*Meninges consisting of the pia mater.

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=== Slide 14: Cerebellum (H&E) ===

The outer portion of the cerebellum, the cortex, is made up of a molecular layer and a granular layer. At the junction between these two layers are the large cell bodies of Purkinje cells. These cells are characteristic of cerebellum. They contain numerous dendrites that extend into the molecular layer and a single axon.

The central portion of the cerebellum consists of myelinated fibers which make up the white matter.

The choroid plexuses are located in the ventricular system of the brain and produce cerebrospinal fluid. Each choroid plexus consists of a vascular stroma covered by columnar epithelial cells, which form large frond-like masses. The cerebrospinal fluid produced in the ventricles flows out through exit foramina at the base of the brain and circulates in the subarachnoid space. It is reabsorbed by the venous sinuses in the dura.

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=== Slide 15: Choroid plexus (Masson) ===
[[File:HistologicChapter6BrainSagittalSectionLabeled.jpg|thumb|200px|Brain Sagittal Section Labeled]]
On this trichrome stained section of choroid plexus note the multiple fronds of tissue. Each is covered with ependymal cells and has a connective tissue infrastructure.

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== Spinal Cord - General Structure ==
[[File:HistologicChapter6SpinalCord.jpg|thumb|200px|Spinal Cord]]
The spinal cord is composed of two principal parts extending the length of the cord, the inner core of gray matter and an outer layer of white matter. The entire cord is supported in a framework of neuroglia. In the most peripheral part of the cord, processes of fibrous astrocytes condense to form the marginal glial membrane, in which nerve fibers are absent.

The gray matter is in the form of two large lateral masses connected by a narrow strip across the midline, the gray commissure, in which lies the central canal, which is largely obliterated in the adult. Each lateral gray mass has a dorsal gray horn or column, a ventral gray horn or column, and an intermediate gray area. The configuration of the gray matter varies in different parts of the cord; the ventral horns are widest in the cervical and lumbar enlargements in which are located the anterior horn cells that innervate the upper and lower extremities respectively, and narrowest in the thoracic segments.

All neuron cell bodies, together with their dendrites and initial portions of their dendrites and initial portions of their axons, are in the gray matter. Unmyelinated nerve fibers course everywhere as well as some myelinated fibers (terminations of incoming sensory fibers or tract fibers in the white matter). Blood vessels are prevalent.

The white matter is composed of nerve fibers, most of which are myelinated, connective tissue septa with blood vessels coming in from the pia matter, and neuroglia septa. Dorsal roots (incoming sensory fibers) are attached to the dorsal lateral surface of the cord (dorsolateral sulcus), and ventral roots to the ventrolateral surface (ventrolateral sulcus). In relation to these, the white matter is divided into the dorsal white columns, lateral white columns, and ventral white columns. Ventrally, there is a deep medial ventral fissure, and dorsally a shallow medial sulcus.
The cord is covered with meninges consisting of the outermost thick fibrous dura mater, a subdural space, the arachnoid and subarachnoid space with arachnoid trabeculae which contains cerebrospinal fluid, and the pia mater, a fibrous membrane attached to the spinal cord. The latter two membranes are often referred to as the pia-arachnoid. From the pia mater, connective tissue septa carrying blood vessels penetrate the white and gray matter.

When dorsal root fibers enter the cord and ventral root fibers first leave the cord, they lie in the subarachnoid space. As they move laterally to exit through the intervertebral foramina, the dura mater continues over them as epineurium. The arachnoid fades out quickly.

=== Slide 97: Lumbar Cord With Meninges, Three-Year Old Child (H&E) ===

With H&E, details of neuron cell bodies are seen quite well; other tissues stain much as in other organs.

Distinguish the general regions of the cord:
*The H-shaped gray matter with its dorsal gray columns, the broad ventral columns, and the intermediate gray area.
*The white matter with its three divisions.
*The delicate dorsal medial (posterior) septum of neuroglia and the ventral fissure.
*The thick dura mater (dense fibrous connective tissue) - the outermost layer of the meninges.
*The central canal in the gray commissure. It is lined with ependymal cells, which have a columnar shape; some may have flagella.

White matter.

*Note innumerable myelinated fibers, mostly in cross sections, since these are mainly ascending and descending tracts. Myelin is not preserved; a clear space remains. The axon is unstained or faintly seen, or it may not be present.
*Thin connective tissue septa and small blood vessels can be seen. Look for perivascular spaces around the blood vessels - clear spaces that are actinically enlarged due to shrinkage of tissues.
*The numerous small nuclei seen are mainly those of fibrous astrocytes and oligodendroglia.
*Identify the marginal glial membrane. It forms the most peripheral part of the spinal cord, is formed by processes of fibrous astrocytes, and lacks nerve fibers.

Dorsal gray columns.

*Note the uppermost large pale area (substantia gelatinosa), the more fibrillar base of the dorsal horn, and myelinated fibers sweeping into these areas from the dorsal white columns (incoming sensory fibers).
*The small nuclei are astrocyte and oligodendroglia nuclei. Small neuron cell bodies are not easily seen.
*Some of the sections may show the actual entrance of the dorsal roots.

Ventral gray columns - general. The columns are broad.

Note the meshwork of fine fibers throughout (unmyelinated nerve fibers, processes of astrocytes), nuclei of astrocytes and oligodendrocytes, small blood vessels in their perivascular spaces, and large anterior horn cells.

The anterior horn cells (Motor Neurons)

*In sections, entire cells are rarely seen, but note the multipolar shapes of the cells, parts of cell processes, Nissl bodies, in the neuroplasm and the distinctive nucleus and nucleolus. Dendrites are short processes that contain Nissl bodies. Look for a cell that shows a clear axon hillock and an emerging axon.

*Note the perineuronal space (exaggerated in sections) around each cell body with occasional perineuronal satellite cells close to the cell body. Satellite cells are astrocytes and/or oligodendrocytes.

*Axons of these anterior horn cells can be seen in groups passing down into the ventral white matter to emerge to form the ventral roots. They innervate the muscles of the lower extremities.

*Innumerable nuclei of neuroglia cells are seen everywhere throughout the gray matter; their cytoplasmic processes shrink to invisibility. Identify astrocytes and oligodendrocytes.

Astrocytes have rounded, somewhat lightly-staining (vesicular) nuclei; they vary in size.

Oligodendrocytes have small, darker-stained nuclei, much like a miniature lymphocyte.

Microglia are not as numerous nor as easily identified (do NOT try to identify them). Microglia are phagocytic cells derived from monocytes.

Look for very small internuncial (connector) neurons scattered throughout the ventral gray. They are typical, but small, neurons. These are interposed between sensory and motor neurons in reflex pathways.

Meninges of the spinal cord.

*Distinguish the pia mater of fibrous connective tissue immediately around the cord.

*In the subarachnoid space, note bundles (fasciculi) of nerve fibers - rootlets of dorsal and ventral roots.

*Distinguish the arachnoid membrane (if not torn) forming the peripheral boundary of the space - a thin connective tissue membrane covered with a layer of squamous cells. It sends fine trabeculae across the space.

*The dense fibrous dura mater lies external to the arachnoid. A subdural space lies between the dura and arachnoid.

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== Sympathetic Chain Ganglion With Multipolar Neurons ==

These are the post-ganglionic visceral efferent neurons. Axons of neurons in the lateral sympathetic nucleus of the thoracic cord had come to the sympathetic chain via the white rami communicantes. Many have synapsed on these ganglion cells. (Others pass through the chain to synapse elsewhere.)

=== Slide 16: Sympathetic Ganglion (H&E) ===

This ganglion has an epineurium but many ganglia do not show such a distinct capsule.

The ganglion cells are more loosely arranged than in the spinal ganglion. Connective tissue stroma is more apparent, also septa with blood vessels.

Ganglion cells are more uniform in size. All are multipolar.

Note typical characteristics of neuron cell bodies: nuclei may be eccentrically placed, an occasional cell is binucleated, and a few cells have yellow pigment. These are normal features of sympathetic ganglion cells.

Perineuronal spaces are less constant, satellite and capsule cells are more variable in number but are present.

Nerve fibers in the stroma are largely unmyelinated or finely myelinated, and less easily identified with routine stains.

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== Parasympathetic Ganglia ==

These are in the walls of organs. Preganglionic parasympathetic fibers go from the cell bodies in the brain stem or sacral spinal cord to the organs to be innervated and synapse on small, typical multipolar neuron cell bodies in ganglia (post-ganglionic neurons). Postganglionic fibers (axons) of these are then distributed to smooth muscle and glands.

=== Slide 94: Colon (H&E) ===

Between the two muscle layers of the esophagus and all subsequent parts of the digestive tract, is a chain of parasympathetic ganglia and vagus nerve fibers (myenteric plexus of Auerbach). The fibers are finely myelinated or unmyelinated. Groups of ganglion cells are seen intermittently within the chain. Look for lightly stained areas between the muscle layers and note:

Small nerves surrounded by a thin perineurium. The numerous nuclei within the nerve are nuclei of neurolemma cells (Schwann cells) or fibroblasts of the endoneurium.

Varying numbers of multipolar ganglion cells (only parts of cells may be seen).

Look for a complete cell that shows the characteristic nucleus and nucleolus. Nuclei may be eccentrically located.

Perineuronal spaces, capsule cells, and satellite cells are present but not as consistent as in the large dorsal root ganglion cells.

The interstitial material is unmyelinated nerve fibers and endoneurium.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 6

2014-07-10T21:02:14Z

Seung Park:

== Introduction ==
[[File:HistologicChapter6Neurons.jpg|thumb|200px|Neurons]]
Nervous tissue is highly specialized to form the nervous system which is organized into two major divisions: The central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of all the nervous tissue lying outside of the brain and the spinal cord. This is subdivided into the cerebrospinal portion (the 12 pairs of cranial nerves, 31 pairs of spinal nerves and associated ganglia) and the autonomic nervous system (sympathetic and parasympathetic components) which deals with visceral activities (smooth muscle, cardiac muscle, and glandular secretions). These parts of the nervous system are not separate entities but are structurally and functionally interdependent. The nerves of the peripheral nervous system are widely distributed throughout the body, extending into all tissues and organs.

The structural and functional unit of the nervous system is the neuron, which is defined as a nerve cell body and all of its processes. Nerve cell bodies are located with the CNS and in the various ganglia outside of the CNS. The processes are dendrites and axons. Neurons function in cooperating groups or chains, some receiving the excitation and passing it on to others, often in many relays, until somewhere in the body a response is affected. Structurally, neurons are classified as multipolar, bipolar, and unipolar according to the number of processes arising from the cell body.

A nerve is a collection or aggregation of nerve fibers outside the CNS, surrounded by a sheath of connective tissue and supported by connective tissue stroma. A nerve fiber consists of an axonal process enveloped with one or two sheaths (myelin sheath and/or neurolemma or Schwann’s sheath).

A ganglion is a group of nerve cell bodies located outside of the central nervous system. These are termed: cranial ganglia, dorsal root ganglia, sympathetic ganglia, and parasympathetic ganglia.

== Nerve Fibers And Nerves ==

=== Slide 27: Peripheral Nerve (Osmium), Cross and Longitudinal Sections ===

Osmium stains myelin, therefore the myelin sheaths will be black, unmyelinated fibers are vaguely outlined, other structures do not stain.

These are sections of a typical peripheral nerve, which contains myelinated fibers of various sizes as well as unmyelinated fibers. Note--axons always shrink in routinely prepared sections.

Look first at the cross section.

Note the epineurium surrounding the entire nerve and sending extensions between the fasciculi (interfascicular CONNECTIVE TISSUE).

Note perineurium surrounding each large fasciculus of nerve fibers. The “cracks” or spaces in some of the fasciculi were sites of smaller perineurial septa.

Within each fasciculus, note myelinated nerve fibers of different sizes. The axon may be faintly apparent (shrunken) or completely unstained.

Focus carefully to see very small thinly myelinated fibers. Unmyelinated fibers are virtually impossible to distinguish.

Look at the longitudinal section

Identify the same structures as above, also fat cells stained with osmium, in the epineurium.

In good longitudinal sections of the larger fibers look for the nodes of Ranvier, but they are not easily seen because of tissue contraction.

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=== Slide 50: Peripheral Nerve (Masson’s Stain) ===

Connective tissue stains blue, nuclei are dark blue, and myelin is orange-red.

Repeat the study of the cross and longitudinal sections as for slide 27 but now detailed structure can be seen. The perineurium should stain blue, but it may be partially red, probably because of inability of the blue stain to completely penetrate this dense tissue.

Note especially that perineurial septa and endoneurium are seen distinctly. The nuclei that appear to be in the endoneurium are fibroblast nuclei of the endoneurium and neurolemma cell (Schwann cell) nuclei; do not try to distinguish between them, but the majority are neurolemma (Schwann) nuclei.

In the nerve fibers, the axon may or may not be stained. Myelin is partly removed from the myelin sheath, leaving the neurokeratin network.

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=== Slide 13: Peripheral Nerve (H&E) ===

Check the same features as previously described, in this cross-section, to see their appearance with a routine stain.

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== Central Nervous System: Brain ==
[[File:HistologicChapter6Brain.jpg|thumb|200px|Brain: Meninges]]
The central nervous system (CNS) comprises the brain and spinal cord. These areas contain nerve cells and their processes, along with specialized support cells.

The specialized support cells of the CNS are collectively called glia. These are astrocytes, oligodendrocytes, ependyma and microglial cells. Astrocytes are stellate cells that are involved in fluid transport and structural support. The stellate morphology is not evident in conventional H&E sections because the processes merge with the processes of other cells, but is seen with special staining methods. Two types of astrocyte have been identiﬁed. Fibrous astrocytes are most evident in the white matter and have long cell processes which are rich in bundles of glial ﬁbrillary acidic protein (GFAP). Protoplasmic astrocytes are most evident in the gray matter of the brain and have long thin processes containing few bundles of GFAP.

One important structural adaptation of astrocytes is seen in their interaction with the blood vessels of the brain, which they surround by forming flat plates termed end feet. The interaction induces changes in the structure of the cerebral vascular endothelium, rendering it highly impermeable, so that it acts as a barrier to diffusion between the blood and the brain, the “blood-brain-barrier”.

Oligodendrocytes are the myelin-producing cells of the CNS, each cell sending out several cell processes and myelinating several nearby axons. In routine histologic sections their branching morphology is not seen, but they do show a rounded nucleus with moderately dense-staining chromatin and, in most preparations, a cytoplasm containing a clear ‘halo’ around the nucleus. Such a halo is an artifact of preparation because oligodendrocytes are fragile and contain few cytoskeletal elements.

Ependymal cells are epithelial like cells that line the cavities in the brain (ventricles) and the central canal of the spinal cord, forming a sheet of cuboidal cells in contact with the cerebrospinal fluid. Each ependymal cell has a small oval basal nucleus with dense chromatin, and many are ciliated. Unlike other epithelial cells, the ependymal cells do not lie on a basement membrane but have tapering processes which merge with the processes of underlying astrocytic cells.

The CNS has its own unique set of immune cells, the main type being the microglial cells, which are specialized macrophages. In conventional H&E preparations microglial cells are not easily seen, appearing only as rod-shaped nuclei with no discernible cytoplasmic borders. The phenotype of microglia suggests that they are similar to dendritic antigen-presenting cells, having a low level of phagocytic activity and expressing class II major histocompatibility molecules.

In disease states microglial cells become activated and increase in size and number. Under these circumstances they are usually supplemented by monocytes, which enter the brain from the blood and form macrophagic cells. The brain appears to have only a very small traffic of lymphoid cells in the normal state.

The CNS has three protective coats, the meninges, which are composed of ﬁbrocollagenous support tissue and epithelial cells. These three layers are: the dura, the arachnoid and the pia.

The dura is a tough ﬁbrocollagenous layer, which forms the outer coat of the CNS. It blends with the periosteum of the skull and is attached to the periosteum of the vertebral canal by the dentate ligaments. It is covered on its internal surface by an incomplete layer of flat epithelial cells. The dura is reflected down from the skull to form sheets of tissue, the tentorium cerebelli and the falx cerebri, which separate the structures of the brain. The venous sinuses of the brain run at the base of these sheets of dura.
The arachnoid is a layer of ﬁbrocollagenous tissue covered by inconspicuous flat epithelial cells and is located beneath, but not anchored to, the dura. Web-like strands of ﬁbrocollagenous tissue extend down from the arachnoid into the subarachnoid space, which contains the cerebrospinal fluid. The main arteries and veins to and from the brain run in the subarachnoid space.

The pia is a delicate layer of epithelial cells associated with loose ﬁbrocollagenous tissue. It lies external to a basement membrane which completely surrounds the CNS.

=== Slide 72: Cerebral Cortex (H&E) ===

With H&E, the meninges as well as the various layers of the cerebral cortex are visible. Distinguish the general regions of the cerebral cortex:

*White matter.
Note few cells per unit area. Cells in the white matter are microglia with few if any neuron bodies.

*Gray matter (cerebral cortex).
The cerebral cortex is divided into six layers. Distinguishing the exact borders of these layers is difficult requiring special staining and is beyond the scope of this discussion. The six layers from outside to inside include: plexiform or molecular layer, small pyramidal cell layer, medium pyramidal cell layer, granular layer, large pyramidal cell layer, and the polymorphic cell layer.

*Meninges consisting of the pia mater.

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=== Slide 14: Cerebellum (H&E) ===

The outer portion of the cerebellum, the cortex, is made up of a molecular layer and a granular layer. At the junction between these two layers are the large cell bodies of Purkinje cells. These cells are characteristic of cerebellum. They contain numerous dendrites that extend into the molecular layer and a single axon.

The central portion of the cerebellum consists of myelinated fibers which make up the white matter.

The choroid plexuses are located in the ventricular system of the brain and produce cerebrospinal fluid. Each choroid plexus consists of a vascular stroma covered by columnar epithelial cells, which form large frond-like masses. The cerebrospinal fluid produced in the ventricles flows out through exit foramina at the base of the brain and circulates in the subarachnoid space. It is reabsorbed by the venous sinuses in the dura.

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=== Slide 15: Choroid plexus (Masson) ===
[[File:HistologicChapter6BrainSagittalSectionLabeled.jpg|thumb|200px|Brain Sagittal Section Labeled]]
On this trichrome stained section of choroid plexus note the multiple fronds of tissue. Each is covered with ependymal cells and has a connective tissue infrastructure.

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== Spinal Cord - General Structure ==
[[File:HistologicChapter6SpinalCord.jpg|thumb|200px|Spinal Cord]]
The spinal cord is composed of two principal parts extending the length of the cord, the inner core of gray matter and an outer layer of white matter. The entire cord is supported in a framework of neuroglia. In the most peripheral part of the cord, processes of fibrous astrocytes condense to form the marginal glial membrane, in which nerve fibers are absent.

The gray matter is in the form of two large lateral masses connected by a narrow strip across the midline, the gray commissure, in which lies the central canal, which is largely obliterated in the adult. Each lateral gray mass has a dorsal gray horn or column, a ventral gray horn or column, and an intermediate gray area. The configuration of the gray matter varies in different parts of the cord; the ventral horns are widest in the cervical and lumbar enlargements in which are located the anterior horn cells that innervate the upper and lower extremities respectively, and narrowest in the thoracic segments.

All neuron cell bodies, together with their dendrites and initial portions of their dendrites and initial portions of their axons, are in the gray matter. Unmyelinated nerve fibers course everywhere as well as some myelinated fibers (terminations of incoming sensory fibers or tract fibers in the white matter). Blood vessels are prevalent.

The white matter is composed of nerve fibers, most of which are myelinated, connective tissue septa with blood vessels coming in from the pia matter, and neuroglia septa. Dorsal roots (incoming sensory fibers) are attached to the dorsal lateral surface of the cord (dorsolateral sulcus), and ventral roots to the ventrolateral surface (ventrolateral sulcus). In relation to these, the white matter is divided into the dorsal white columns, lateral white columns, and ventral white columns. Ventrally, there is a deep medial ventral fissure, and dorsally a shallow medial sulcus.
The cord is covered with meninges consisting of the outermost thick fibrous dura mater, a subdural space, the arachnoid and subarachnoid space with arachnoid trabeculae which contains cerebrospinal fluid, and the pia mater, a fibrous membrane attached to the spinal cord. The latter two membranes are often referred to as the pia-arachnoid. From the pia mater, connective tissue septa carrying blood vessels penetrate the white and gray matter.

When dorsal root fibers enter the cord and ventral root fibers first leave the cord, they lie in the subarachnoid space. As they move laterally to exit through the intervertebral foramina, the dura mater continues over them as epineurium. The arachnoid fades out quickly.

=== Slide 97: Lumbar Cord With Meninges, Three-Year Old Child (H&E) ===

With H&E, details of neuron cell bodies are seen quite well; other tissues stain much as in other organs.

Distinguish the general regions of the cord:
*The H-shaped gray matter with its dorsal gray columns, the broad ventral columns, and the intermediate gray area.
*The white matter with its three divisions.
*The delicate dorsal medial (posterior) septum of neuroglia and the ventral fissure.
*The thick dura mater (dense fibrous connective tissue) - the outermost layer of the meninges.
*The central canal in the gray commissure. It is lined with ependymal cells, which have a columnar shape; some may have flagella.

White matter.

*Note innumerable myelinated fibers, mostly in cross sections, since these are mainly ascending and descending tracts. Myelin is not preserved; a clear space remains. The axon is unstained or faintly seen, or it may not be present.
*Thin connective tissue septa and small blood vessels can be seen. Look for perivascular spaces around the blood vessels - clear spaces that are actinically enlarged due to shrinkage of tissues.
*The numerous small nuclei seen are mainly those of fibrous astrocytes and oligodendroglia.
*Identify the marginal glial membrane. It forms the most peripheral part of the spinal cord, is formed by processes of fibrous astrocytes, and lacks nerve fibers.

Dorsal gray columns.

*Note the uppermost large pale area (substantia gelatinosa), the more fibrillar base of the dorsal horn, and myelinated fibers sweeping into these areas from the dorsal white columns (incoming sensory fibers).
*The small nuclei are astrocyte and oligodendroglia nuclei. Small neuron cell bodies are not easily seen.
*Some of the sections may show the actual entrance of the dorsal roots.

Ventral gray columns - general. The columns are broad.

Note the meshwork of fine fibers throughout (unmyelinated nerve fibers, processes of astrocytes), nuclei of astrocytes and oligodendrocytes, small blood vessels in their perivascular spaces, and large anterior horn cells.

The anterior horn cells (Motor Neurons)

*In sections, entire cells are rarely seen, but note the multipolar shapes of the cells, parts of cell processes, Nissl bodies, in the neuroplasm and the distinctive nucleus and nucleolus. Dendrites are short processes that contain Nissl bodies. Look for a cell that shows a clear axon hillock and an emerging axon.

*Note the perineuronal space (exaggerated in sections) around each cell body with occasional perineuronal satellite cells close to the cell body. Satellite cells are astrocytes and/or oligodendrocytes.

*Axons of these anterior horn cells can be seen in groups passing down into the ventral white matter to emerge to form the ventral roots. They innervate the muscles of the lower extremities.

*Innumerable nuclei of neuroglia cells are seen everywhere throughout the gray matter; their cytoplasmic processes shrink to invisibility. Identify astrocytes and oligodendrocytes.

Astrocytes have rounded, somewhat lightly-staining (vesicular) nuclei; they vary in size.

Oligodendrocytes have small, darker-stained nuclei, much like a miniature lymphocyte.

Microglia are not as numerous nor as easily identified (do NOT try to identify them). Microglia are phagocytic cells derived from monocytes.

Look for very small internuncial (connector) neurons scattered throughout the ventral gray. They are typical, but small, neurons. These are interposed between sensory and motor neurons in reflex pathways.

Meninges of the spinal cord.

*Distinguish the pia mater of fibrous connective tissue immediately around the cord.

*In the subarachnoid space, note bundles (fasciculi) of nerve fibers - rootlets of dorsal and ventral roots.

*Distinguish the arachnoid membrane (if not torn) forming the peripheral boundary of the space - a thin connective tissue membrane covered with a layer of squamous cells. It sends fine trabeculae across the space.

*The dense fibrous dura mater lies external to the arachnoid. A subdural space lies between the dura and arachnoid.

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== Sympathetic Chain Ganglion With Multipolar Neurons ==

These are the post-ganglionic visceral efferent neurons. Axons of neurons in the lateral sympathetic nucleus of the thoracic cord had come to the sympathetic chain via the white rami communicantes. Many have synapsed on these ganglion cells. (Others pass through the chain to synapse elsewhere.)

=== Slide 16: Sympathetic Ganglion (H&E) ===

This ganglion has an epineurium but many ganglia do not show such a distinct capsule.

The ganglion cells are more loosely arranged than in the spinal ganglion. Connective tissue stroma is more apparent, also septa with blood vessels.

Ganglion cells are more uniform in size. All are multipolar.

Note typical characteristics of neuron cell bodies: nuclei may be eccentrically placed, an occasional cell is binucleated, and a few cells have yellow pigment. These are normal features of sympathetic ganglion cells.

Perineuronal spaces are less constant, satellite and capsule cells are more variable in number but are present.

Nerve fibers in the stroma are largely unmyelinated or finely myelinated, and less easily identified with routine stains.

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== Parasympathetic Ganglia ==

These are in the walls of organs. Preganglionic parasympathetic fibers go from the cell bodies in the brain stem or sacral spinal cord to the organs to be innervated and synapse on small, typical multipolar neuron cell bodies in ganglia (post-ganglionic neurons). Postganglionic fibers (axons) of these are then distributed to smooth muscle and glands.

=== Slide 94: Colon (H&E) ===

Between the two muscle layers of the esophagus and all subsequent parts of the digestive tract, is a chain of parasympathetic ganglia and vagus nerve fibers (myenteric plexus of Auerbach). The fibers are finely myelinated or unmyelinated. Groups of ganglion cells are seen intermittently within the chain. Look for lightly stained areas between the muscle layers and note:

Small nerves surrounded by a thin perineurium. The numerous nuclei within the nerve are nuclei of neurolemma cells (Schwann cells) or fibroblasts of the endoneurium.

Varying numbers of multipolar ganglion cells (only parts of cells may be seen).

Look for a complete cell that shows the characteristic nucleus and nucleolus. Nuclei may be eccentrically located.

Perineuronal spaces, capsule cells, and satellite cells are present but not as consistent as in the large dorsal root ganglion cells.

The interstitial material is unmyelinated nerve fibers and endoneurium.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 2

2014-07-09T19:33:49Z

Seung Park: /* Microscopic Study: Mitosis (Iron H) */

== Cells, Organelles, and Inclusions ==
[[File:HistologicChapter2Cell.jpg|thumb|200px|Cell schematic]]
To begin the study of cellular structure, you are asked to identify several kinds of cells, cellular specializations and inclusions of cells. Learn to distinguish between the nucleolus, the nucleus, and the cytoplasm of a cell. Observe the appearance of the chromatin, the position of the nucleus within the cell and the staining characteristics of the cytoplasm. Note the size of the cells, the density of similar cells, and their arrangement in the tissue. As you study the different cell types, keep in mind that sectioned material is being observed and that the appearance of the cell may vary depending on the plane of section.

A cell usually contains only one nucleus, but some cells may be binucleate. The nucleus often conforms to the shape of the cell being spherical, ovoid, or elongated. Other nuclei may be crescent shaped or lobated. It can be flattened towards the base of the cell when the pressure from cytoplasmic constituents “pushes it” there. Nucleoli may or may not be present. In sectioned material, the nucleus or nucleolus may appear to be absent from a cell because they were not in the plane of sectioning. If the cell is in a phase of mitosis, the nucleus will appear different from nuclei of other non-mitotic cells of the tissue.

The cytoplasm often exhibits modifications according to the specific functions of the cell or the tissue. Muscle cells have contractile myofibrils. Secretory cells of the salivary glands possess numerous secretory granules. Epithelial cells of the skin produce a protein called keratin for protection. The epithelial lining of the respiratory tract may possess cilia. White blood cells may contain primary and specific granules. Neurons possess neurofibrils, etc. The list is almost endless.

NOTE: The objective of this first exercise is merely to gain an awareness of the varieties of cell sizes, cell shapes, cell types, cell staining characteristics and cell organelles or inclusions. You are not expected, at this time, to become familiar with the over-all structure of the tissues and organs where these cells are located.

=== Microscopic Study: Architecture ===
==== Slide 25: Spinal Cord (Thionin) ====
On slide 25, Spinal Cord (Thionin) find under low power the cell bodies of multipolar neurons located in the two anterior horns of the gray matter (if the slide is held towards the light, the gray matter appears H-shaped). With medium power, identify a cell body containing a large pale nucleus and a darkly stained nucleolus. Study this cell under high power. The irregular, granular-like, basophilic staining masses within the cytoplasm are called Nissl bodies. They consist of free ribosomes and granular endoplasmic reticulum.

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==== Slide 73: Spinal Ganglion (Silver) ====
On slide 73, Spinal Ganglion (silver) identify the large cell bodies of the ganglion cells associated with the sensory root of spinal nerves. The cell bodies of these unipolar neurons range in size from 15μm to 100μm. Compare a number of ganglion cell bodies for size differences. The centrally located nuclei stain palely and appear as clear spaces in the middle of the granular cytoplasm. With careful observation you will see nuclei of much smaller cells immediately surrounding the cell bodies of the ganglion cells. These represent satellite cells. Note how much smaller they are than the nuclei of the ganglion cells.

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==== Slide 149: Liver (H&E) ====
On slide 149, Liver (H&E) observe that the hepatocytes (liver parenchymal cells) appear to be arranged as rows or cords of cells. Actually the tridimensional arrangement of these cells is in cellular sheets or plates which are separated by blood-filled spaces called sinusoids. Red blood corpuscles may be seen in some of the sinusoids. Note that cell boundaries can be distinctly seen between many of the liver cells. The polyhedral- shaped hepatocytes have round, centrally located nuclei containing one or more nucleoli and scattered clumps of chromatin. Binucleated hepatocytes can be found. Note the granularity of the eosinophilic staining cytoplasm

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==== Slide 154: Pancreas (H&E) ====
Slide 154, Pancreas (H&E) has cells which distinctly exhibit a difference between basophilic regions and acidophilic regions. After studying the cells with medium power, turn to high power to complete your study. Observe that the cell boundaries are indistinct. Note that the cytoplasm in the basal region of the acinar cells is basophilic. Here the ribonucleoproteins associated with rough endoplasmic reticulum and the large numbers of mitochondria are sufficiently dense to stain with the basic dye. Note, however, the red staining of the apical half of the acinar cells. This acidophilic staining cytoplasm contains numerous secretory granules that stain brightly with the eosin stain. The nuclei are basophilic staining as are the nuclei of all cells. Observe that the nuclei are characteristically located in the basal one-third of the cell. Nucleoli may be seen in many cells.

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=== Microscopic Study: Cell Types ===
==== Slide 2: Trachea (H&E) ====
[[File:HistologicChapter2Cilia.jpg|thumb|200px|Cilia schematic]]
On slide 2, Trachea (H&E) identify the cilia on the tall cells of the pseudostratified columnar epithelium that line the lumen of the trachea. Each cilium is derived from a basal body, represented here in aggregate by the dark lines where the cilia attach to the cell. In some regions of this tissue the cilia are absent or the entire epithelium is missing. This is artifact.

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==== Slide 89: Skeletal Muscle (H&E) ====
On slide 89, Skeletal Muscle (H&E) identify muscle fibers cut in longitudinal section. Under high power note the striated appearance of the muscle cells. Although not readily visible, the cytoplasm of these cells contains myofibrils, the contractile elements of the cell. The arrangement of these myofibrils and their subunits, the myofilaments, impart the striated appearance to the muscle fibers.

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==== Slide 31: Ileum (H&E) ====
On slide 31, Ileum (H&E) identify with low power the villi projecting from one side of the tissue. With high power identify the tall cells (simple columnar cells) which cover these villi. On the free surface of these cells can be seen a dense line representing the striated border. This border consists of cytoplasmic processes termed microvilli that greatly increase the absorptive area of the small intestine. In light microscopy, the microvilli appear vertically striated so these projections form a “striated border.”

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== Mitosis ==
[[File:HistologicChapter2Mitosis.jpg|thumb|200px|Mitosis schematic]]
Mitosis can be viewed as the means whereby identical genetic material, contained in the chromosomes, is distributed to two daughter nuclei. It can be divided into four stages, each characterized by certain features of nuclear or chromosome morphology and chromosome movement. The stages are arbitrary in that mitosis is a continuous process from its inception at prophase through the stages of metaphase and anaphase to the final stage of telophase. The nucleus of a cell that is not dividing is in the interphase stage.

The number of mitotic figures in a tissue is an index of the rate of turnover of the component cells. In benign tumors, mitotic figures are few in numbers, whereas in malignant tumors, mitotic figures are more numerous and may include many bizarre forms. Hence, the recognition of mitotic figures is one criterion for the interpretation of various kinds of pathology of a tissue.

=== Microscopic Study: Mitosis ===
On slide 34, Mitosis (Iron H), are longitudinal sections of onion root tips in which cells have been fixed in various stages of mitosis. Learn to identify the characteristic arrangement of the chromatin in each state.

==== Slide 34: Mitosis (Iron H) ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 2

2014-07-09T19:33:28Z

Seung Park:

== Cells, Organelles, and Inclusions ==
[[File:HistologicChapter2Cell.jpg|thumb|200px|Cell schematic]]
To begin the study of cellular structure, you are asked to identify several kinds of cells, cellular specializations and inclusions of cells. Learn to distinguish between the nucleolus, the nucleus, and the cytoplasm of a cell. Observe the appearance of the chromatin, the position of the nucleus within the cell and the staining characteristics of the cytoplasm. Note the size of the cells, the density of similar cells, and their arrangement in the tissue. As you study the different cell types, keep in mind that sectioned material is being observed and that the appearance of the cell may vary depending on the plane of section.

A cell usually contains only one nucleus, but some cells may be binucleate. The nucleus often conforms to the shape of the cell being spherical, ovoid, or elongated. Other nuclei may be crescent shaped or lobated. It can be flattened towards the base of the cell when the pressure from cytoplasmic constituents “pushes it” there. Nucleoli may or may not be present. In sectioned material, the nucleus or nucleolus may appear to be absent from a cell because they were not in the plane of sectioning. If the cell is in a phase of mitosis, the nucleus will appear different from nuclei of other non-mitotic cells of the tissue.

The cytoplasm often exhibits modifications according to the specific functions of the cell or the tissue. Muscle cells have contractile myofibrils. Secretory cells of the salivary glands possess numerous secretory granules. Epithelial cells of the skin produce a protein called keratin for protection. The epithelial lining of the respiratory tract may possess cilia. White blood cells may contain primary and specific granules. Neurons possess neurofibrils, etc. The list is almost endless.

NOTE: The objective of this first exercise is merely to gain an awareness of the varieties of cell sizes, cell shapes, cell types, cell staining characteristics and cell organelles or inclusions. You are not expected, at this time, to become familiar with the over-all structure of the tissues and organs where these cells are located.

=== Microscopic Study: Architecture ===
==== Slide 25: Spinal Cord (Thionin) ====
On slide 25, Spinal Cord (Thionin) find under low power the cell bodies of multipolar neurons located in the two anterior horns of the gray matter (if the slide is held towards the light, the gray matter appears H-shaped). With medium power, identify a cell body containing a large pale nucleus and a darkly stained nucleolus. Study this cell under high power. The irregular, granular-like, basophilic staining masses within the cytoplasm are called Nissl bodies. They consist of free ribosomes and granular endoplasmic reticulum.

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==== Slide 73: Spinal Ganglion (Silver) ====
On slide 73, Spinal Ganglion (silver) identify the large cell bodies of the ganglion cells associated with the sensory root of spinal nerves. The cell bodies of these unipolar neurons range in size from 15μm to 100μm. Compare a number of ganglion cell bodies for size differences. The centrally located nuclei stain palely and appear as clear spaces in the middle of the granular cytoplasm. With careful observation you will see nuclei of much smaller cells immediately surrounding the cell bodies of the ganglion cells. These represent satellite cells. Note how much smaller they are than the nuclei of the ganglion cells.

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==== Slide 149: Liver (H&E) ====
On slide 149, Liver (H&E) observe that the hepatocytes (liver parenchymal cells) appear to be arranged as rows or cords of cells. Actually the tridimensional arrangement of these cells is in cellular sheets or plates which are separated by blood-filled spaces called sinusoids. Red blood corpuscles may be seen in some of the sinusoids. Note that cell boundaries can be distinctly seen between many of the liver cells. The polyhedral- shaped hepatocytes have round, centrally located nuclei containing one or more nucleoli and scattered clumps of chromatin. Binucleated hepatocytes can be found. Note the granularity of the eosinophilic staining cytoplasm

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==== Slide 154: Pancreas (H&E) ====
Slide 154, Pancreas (H&E) has cells which distinctly exhibit a difference between basophilic regions and acidophilic regions. After studying the cells with medium power, turn to high power to complete your study. Observe that the cell boundaries are indistinct. Note that the cytoplasm in the basal region of the acinar cells is basophilic. Here the ribonucleoproteins associated with rough endoplasmic reticulum and the large numbers of mitochondria are sufficiently dense to stain with the basic dye. Note, however, the red staining of the apical half of the acinar cells. This acidophilic staining cytoplasm contains numerous secretory granules that stain brightly with the eosin stain. The nuclei are basophilic staining as are the nuclei of all cells. Observe that the nuclei are characteristically located in the basal one-third of the cell. Nucleoli may be seen in many cells.

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=== Microscopic Study: Cell Types ===
==== Slide 2: Trachea (H&E) ====
[[File:HistologicChapter2Cilia.jpg|thumb|200px|Cilia schematic]]
On slide 2, Trachea (H&E) identify the cilia on the tall cells of the pseudostratified columnar epithelium that line the lumen of the trachea. Each cilium is derived from a basal body, represented here in aggregate by the dark lines where the cilia attach to the cell. In some regions of this tissue the cilia are absent or the entire epithelium is missing. This is artifact.

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==== Slide 89: Skeletal Muscle (H&E) ====
On slide 89, Skeletal Muscle (H&E) identify muscle fibers cut in longitudinal section. Under high power note the striated appearance of the muscle cells. Although not readily visible, the cytoplasm of these cells contains myofibrils, the contractile elements of the cell. The arrangement of these myofibrils and their subunits, the myofilaments, impart the striated appearance to the muscle fibers.

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==== Slide 31: Ileum (H&E) ====
On slide 31, Ileum (H&E) identify with low power the villi projecting from one side of the tissue. With high power identify the tall cells (simple columnar cells) which cover these villi. On the free surface of these cells can be seen a dense line representing the striated border. This border consists of cytoplasmic processes termed microvilli that greatly increase the absorptive area of the small intestine. In light microscopy, the microvilli appear vertically striated so these projections form a “striated border.”

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== Mitosis ==
[[File:HistologicChapter2Mitosis.jpg|thumb|200px|Mitosis schematic]]
Mitosis can be viewed as the means whereby identical genetic material, contained in the chromosomes, is distributed to two daughter nuclei. It can be divided into four stages, each characterized by certain features of nuclear or chromosome morphology and chromosome movement. The stages are arbitrary in that mitosis is a continuous process from its inception at prophase through the stages of metaphase and anaphase to the final stage of telophase. The nucleus of a cell that is not dividing is in the interphase stage.

The number of mitotic figures in a tissue is an index of the rate of turnover of the component cells. In benign tumors, mitotic figures are few in numbers, whereas in malignant tumors, mitotic figures are more numerous and may include many bizarre forms. Hence, the recognition of mitotic figures is one criterion for the interpretation of various kinds of pathology of a tissue.

=== Microscopic Study: Mitosis (Iron H) ===
On slide 34, Mitosis (Iron H), are longitudinal sections of onion root tips in which cells have been fixed in various stages of mitosis. Learn to identify the characteristic arrangement of the chromatin in each state.

==== Slide 34: Mitosis (Iron H) ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 5

2014-07-09T19:29:56Z

Seung Park:

== Introduction ==

Muscle, one of the four basic tissues, is highly specialized for contractility. The fundamental unit of muscle is the muscle cell (usually called a muscle fiber or just “fiber”) which shortens in its long axis upon stimulation. The contraction occurs when two types of filaments, actin and myosin, interact with each other to interdigitate, thus pulling the two ends of the fibers closer together. The three kinds of muscle are smooth muscle, skeletal muscle, and cardiac muscle. The latter two are called striated muscle because of microscopically visible cross striations exhibited by the fibers. Smooth muscle lacks cross striations.

== Smooth Muscle ==

=== Slide 31: Ileum (H&E) ===

On slide 31, Ileum (H&E), identify smooth muscle fibers in the relatively thick muscle coat (muscularis). The muscle fibers are arranged in two well-defined layers: An inner circular and an outer longitudinal. Between the two layers of muscle is a thin layer of connective tissue that varies in thickness and contains a plexus of nerve fibers and also parasympathetic ganglion cells known as the myenteric plexus (of Auerbach).

In the outer muscle layer, where the smooth muscle fibers are cut in longitudinal section, observe the shape of the smooth muscle cell (fiber), its size, the amount of sarcoplasm, and the position of the nucleus. Note the elongated shape of the smooth muscle nuclei as compared to nearby fibroblast nuclei in the connective tissue septa. With medium power, scan this outer muscular layer and notice how the smooth muscle is arranged in the form of broad sheets or bands.

Now look at the inner muscle layer where the smooth muscle fibers are cut transversely. Observe that the nucleus is not always seen. Why? When it is seen, notice how it varies in size in relation to the diameter of the fiber. Note especially the position of the nucleus within the fiber.

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=== Slide 121: Urinary Bladder (H&E) ===

On slide 121, Urinary bladder (H&E), notice how the smooth muscle fibers of the thick muscle coat are arranged as interlacing bundles. Each bundle is supported by moderately dense connective tissue. The arrangement increases the efficiency of expelling urine quickly as well as increases the ability of the organ to withstand the force of distension as urine accumulates within the bladder.

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== Skeletal Muscle ==
[[File:HistologicChapter5SkeletalMuscle.jpg|thumb|200px|Skeletal Muscle Diagram]]

=== Slide 20: Skeletal Muscle (H&E) ===

On slide 20, Skeletal muscle (H&E), is one of the muscles in the larynx whose fibers appear more loosely arranged because of edema in the connective tissues; therefore, individual fibers can be seen more easily. The muscle fibers are sectioned in various planes. Keep in mind the large size (diameter) of skeletal muscle fibers as compared with smooth muscle fibers.

Look at the muscle fibers in longitudinal section. Note: The fibers are long and approximately uniform in diameter; cross-striations are visible varying in distinctness in different fibers; fibers are multinucleated with nuclei at the periphery of the fiber; a thin sarcolemma (plasmalemma) covers the fibers.

Select a well-stained longitudinal fiber in which cross-striations are readily visible with low power (10 x). Study the striations. At 40 x power the dark A bands and the light I bands can be distinguished, and the thin Z line in the I band can sometimes be seen.
While the A band remains constant in width, the I band width varies according to the state of contraction: Very narrow if muscle was contracted at time of fixation, or wider if muscle was fixed in a relaxed or post-contraction state. An additional band, the H band (a lighter area within the A band) is rarely visible with the light microscope. The segment between two Z-lines is a sarcomere - the function unit of all striated muscle (skeletal and cardiac). With H&E, the Z-lines appear as fine red lines.

In cross section, note the uniform diameter of the fibers and the peripherally located nuclei. In a good cross section, the myofibrils appear as pinpoints. Oblique sections are neither cross nor longitudinal and characteristics are not always well demonstrated.
Note the fine loose connective tissue between muscle fibrils (endomysium). It is easily seen here.

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=== Slide 8: Intervertebral Disc (H&E) ===

Slide 8, Intervertebral disc (H&E). Some of the deep back muscle fibers attach directly to the periosteum by means of short tendons or by an apparent continuity between muscle and the connective tissue of the periosteum.

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== Cardiac Muscle ==

=== Slide 75: Heart and Purkinje Fibers (H&E) ===

Slide 75, Heart and Purkinje fibers (H&E), shows a portion of the left ventricle with its epicardium and endocardium, the aorta, coronary artery and vein. Purkinje fibers are present in the subendocardial areas. This slide demonstrates the major characteristics of cardiac muscle tissue: branching myocardial fibers, cross-striations, intercalated discs, and a centrally placed nucleus within each muscle fiber.

Myocardial fibers are seen cut longitudinally, obliquely, and transversely. The reason for this orientation is that the muscle fibers of the heart course spirally within the walls of the heart. The spiral arrangement permits efficient filling and expulsion of the blood. In longitudinal sections of muscle observe: the cross-striations of the fibers; size, shape, and location of the nucleus, the clear area at either end of the nucleus and the myofibrils within the sarcoplasm. Note how the intercalated discs (darkly stained lines) extend either straight across the fiber or in step-wise fashion.

Between the myocardial fibers is seen loose connective tissue of the endomysium containing numerous capillaries. The rich vascularity of heart muscle is emphasized.

Locate the lower right-hand part of the large section (interventricular septum) on low power. The thin tissue covering most of the upper and lower margins of the section is endocardium. The endocardium includes the single layer of endothelial cells plus underlying connective tissue With medium and high power find the Purkinje fibers immediately adjacent to the upper and lower endocardium. The latter are modified cardiac fibers specialized to conduct impulses and form part of the impulse-conducting system of the heart. Purkinje fibers are lighter-stained (H&E), contain fewer myofibrils (in cross-section the myofibrils are found to be limited to the periphery of the fiber), and have more sarcoplasmic space surrounding each nucleus than is the case for regular myocardial fibers. Nuclei are more rounded but often appear irregular in outline. Look for longitudinal and cross-sections of the Purkinje fibers.

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=== Slide 91: Cardiac Muscle (Gomori's) ===

On slide 91, Cardiac muscle (Gomori’s), the cross-striations of the myocardial fibers and the intercalated discs are more prominently displayed. The intercalated discs stain as a black line. Between the myocardial fibers the capillaries and other vessels are readily seen; the black bodies within the vessels are primarily erythrocytes. Note the strands of blue-staining connective tissue which accompany the blood vessels and which also comprise part of the endocardium and epicardium. See sketch on next page for location of Purkinje fibers.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 4

2014-07-09T19:28:40Z

Seung Park:

== Loose Connective Tissue ==

=== Slide 94: Loose Connective Tissue in the Colon (H&E) ===

At low power locate the zone of loose connective tissue that lies between the layer of glands and the thick layer of dense, eosinophilic smooth muscle. Many small blood vessels lined with simple squamous epithelium (endothelium) are present in the connective tissue.

With higher power, select a good area of loose tissue and note:
* Collagenous fibers are of various sizes, stained pink with eosin, are coursing in various directions, and are cut in various planes. They appear ragged in sections.
* Fine elastic fibers are present but difficult to distinguish with this stain, also because sectioning will leave only fragments of fibers. Look for some. They will be fine, homogenous threads, poorly stained but somewhat refractile.
* Fibroblasts are shrunken; this is typical in routinely prepared sections. Nuclei are clearly defined and stain darkly. Thin cell processes may be seen on some cells. Other cell types are rare.

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=== Slide 20: Skeletal Muscle and Loose Connective Tissue (H&E) ===

This is a section through one of the muscles of the larynx. Much of the associated connective tissue is very loose because of edema (a complication here because of a skull fracture); the fibers are spread far apart and excessive numbers of cells are present.

Look in the zone of loose connective tissue in the part of the section just beneath the epithelial layer. Note that the fibers course in various directions. Some of the thinnest fibers seen here are probable reticular fibers.

Identify fibroblasts, numerous lymphocytes, and plasma cells.

Look in the small areas of more normal loose connective tissue, nearer the muscle and elsewhere; identify collagenous and elastic fibers.

This slide has groups of mixed glands with a special epithelium that need not be identified, but their ducts may be lined with simple columnar or stratified columnar epithelium.

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=== Slide 28: Loose Connective Tissue With Mast Cells ===

This is abdominal skin from a 3-week old rat, fixed to preserve mast cell granules, stained with toluidine blue (no counter stain).

The surface of the skin is thin stratified squamous epithelium, the subcutaneous connective tissue is young, loose connective tissue.

Identify fibroblasts and thin collagenous fibers (stained very faintly).

Mast cells are abundant. Find some that show the entire cell: oval cell body, cytoplasm filled with purple granules (some may appear vacuolated), and a central small rounded light blue nucleus. Note the large size of the mast cells.

The epithelial-lined structures extending in from the surface epithelium are developing hair follicles.

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=== Slide 144: Colon (PASH) ===

Mast cells are demonstrable in this section of the colon. Look in the deepest part of the layer of glands. They are large oval cells with a small central nucleus and cytoplasm densely packed with prominent PAS-positive granules.

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=== Slide 100: Macrophages Ingesting Trypan Blue ===

Trypan blue, a “vital” dye, is used to demonstrate phagocytic activity of macrophages. A 0.5% solution was injected intraperitoneally into young rats on alternate days for two weeks. Macrophages all over the body ingest the trypan blue particles.

Slide 100, Mesentery and mesenteric lymph nodes, azocarmine. All nuclei stain pinkish-red with azocarmine; other tissues take only a faint background stain.

Look in the connective tissue of the mesentery for macrophages of various sizes with inclusions of trypan blue in their cytoplasm.

The lymph nodes are dense masses of lymphocytes supported in a reticular connective tissue stroma. Look for macrophages in the less dense areas.

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== Dense Connective Tissue ==

=== Slide 3: Dense Irregular Connective Tissue in Scalp (H&E) ===

A thick layer of dense irregular connective tissue underlies the stratified epithelium. Prominent structures seen in this layer are hair follicles, sebaceous glands, and sweat glands. Also present are small blood vessels and scattered fat cells.

Study the connective tissue. Note:
* The density of the connective tissue layer.
* The thick bundles of collagenous fibers, seen in various planes of section - cross, oblique and longitudinal sections.
* Look for thin, refractile elastic fibers. They can be seen with high power and careful focusing.
* Identify fibroblasts. Nuclei are seen, little or no cytoplasm.

Review the structure of stratified squamous epithelium. The eosinophilic, “stringy material” in the uppermost part of the epithelium is the stratum corneum that is sloughing.

The thick wall of the hair follicles is a somewhat modified stratified squamous epithelium continuous with the surface epithelium.

Sebaceous glands, associated with the hair follicles, are composed mainly of rounded cells filled with oily secretion which dissolves in prepared sections, thus leaving vacuolated cells that stain very lightly. The nucleus is centrally placed.

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== Adipose Tissue ==

=== Slide 46: Adipose Tissue in Thick Skin (H&E) ===

Fat is found in the subcutaneous tissue, below the layer of dense irregular connective tissue. It is present largely as adipose tissue.

Scan to locate the adipose tissue.

Recognize fat cells as large, clear cells.

In the larger masses of cells, note connective tissue septa, which form lobules of adipose tissue.

With higher magnifications:

Look at the large, more or less rounded individual fat cells, empty, showing the cell membrane and perhaps some of the rim of cytoplasm. (Fat has been removed during preparation.)

Look for an eccentric nucleus within the fat cell. Every cell will not show one.
Nuclei of fibroblasts are present between fat cells. It is not always easy to distinguish these from fat cell nuclei.

Look at the interlobular septa. What type of connective tissue forms these septa?

Recognize blood vessels in the septa and smaller vessels among the fat cells.

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Look also at slide 3 (scalp) and slide 75 (heart). Locate the areas of adipose tissue and note features as above.

==== Slide 3: Scalp ====

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==== Slide 75: Heart ====

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 3

2014-07-09T19:28:02Z

Seung Park: /* Stratified Epithelium */

== Introduction ==
An epithelium is defined as a tissue that covers or lines the free surfaces of the body. It is one of four fundamental body tissues, with the other three basic tissues being muscle, nervous and connective tissues. Histologically, an epithelium is characterized as being composed of cells sitting upon a basement membrane. The cells are usually arranged in one or more layers with scant intercellular material, or they may sometimes be arranged in cords as in some endocrine glands.

One of the surfaces of an epithelium is exposed either to air or fluid, whereas the other surface is generally attached to a basement membrane that rests upon an underlying connective tissue. With rare exceptions, epithelium is not penetrated by blood vessels and must rely on diffusion processes from the underlying blood supply of the connective tissue for the exchange of nutrients, gases, and wastes (e.g., the endothelial lining of a blood vessel).

Epithelial tissues show numerous specializations of the free surface of cells or of the component cells themselves. For example, the glands of the skin and intestinal tract are derived from epithelium. The embryonic epithelium invaginates into the underlying connective tissue during embryonic development to differentiate into glandular structures. Remember that epithelial tissues are specialized to function in secretion, protection, excretion, absorption, lubrication, sensation, and even reproduction.

One should be able to classify any variety of epithelium according to its structure. An epithelium is usually named according to the appearance of the surface cells. The shape of the cells is important in naming the epithelium. Sometimes the shape referred to is the three dimensional one as in the case of squamous cells (scale-like) and sometimes the two dimensional appearance is referred to as it is seen when the cell is cut vertically to its base. Thus “cuboidal” cells which may appear as squares in sections are actually prismatic in shape with eight sides if seen in their entirety. “Columnar” cells are more elongated prisms. If a cell is surrounded and compressed equally on all sides by other cells, it is usually fourteen sided and appears as a polyhedron in a section.

Identify the following representative varieties of epithelial and be able to interpret the appearance even if it is not cut vertically to the basement membrane.

== Simple Epithelium ==
This type of epithelium has one layer of cells.

=== Simple Squamous Epithelium ===
[[File:HistologicChapter3SimpleSquamousEpithelium.jpg|thumb|200px|Simple squamous epithelium schematic]]
This “pavement epithelium” has flattened scale-like or plate-like cells.

==== Slide 118: Kidney (PASH) ====
On Slide 118, Kidney (PASH) locate the parietal layer of Bowman’s capsule surrounding the glomeruli (blood capillaries). Identify the layer of simple squamous epithelium which forms the parietal layer of Bowman’s capsule. These cells rest on a pink-staining basement membrane. Note that you can see only the nuclei clearly; the attenuated cytoplasm is indistinct.

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==== Slide 18: Spleen (H&E) ====
On slide 18, Spleen (H&E), locate the connective tissue capsule that covers the spleen and note the simple squamous epithelium covering the capsule. This lining is called the mesothelium. A mesothelium is defined as a single layer of flattened cells forming an epithelium that lines serous (body) cavities. Note the shapes of the cells. In some regions, they may appear to be slightly cuboidal.

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=== Simple Cuboidal Epithelium ===
[[File:HistologicChapter3SimpleCuboidalEpithelium.jpg|thumb|200px|Simple cuboidal epithelium schematic]]
In this kind of epthelium, the height of each component cell is approximately equivalent to its width.

==== Slide 114: Kidney (H&E) ====
On slide 114, Kidney (H&E), locate segments of kidney tubules lined with simple cuboidal epithelium. In this type of epithelium the nucleus is round and located in the center of the cell. Other segments of a kidney tubule may be lined by epithelial cells ranging from simple squamous to low columnar or pyramidal (modified columnar) in shape. On slide 118, Kidney (PASH) note how well the PAS stain demonstrates the basement membranes underlying the various epithelial. Cells of different heights are also readily observed on this slide.

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=== Simple Columnar Epithelium ===
[[File:HistologicChapter3SimpleColumnarEpithelium.jpg|thumb|200px|Simple columnar epithelium schematic]]
In this kind of epithelium, the height exceeds the width of the cell.

==== Slide 140: Duodenum (PASH) ====
On slide 140, duodenum, (PASH), observe the layer of columnar cells that cover the villi. The ovoid nuclei are located in the lower one-half of the cells. Study the shapes of the cells, the location of the nuclei and the specialization of the free surface. These columnar cells are absorptive cells that have microvilli forming a striated border and covered by a PAS-positive glycocalyx. Goblet cells, which are columnar cells modified to secrete mucus, can be seen interspersed among the absorptive columnar epithelial cells. The goblets in these cells exhibit heavy PAS staining.

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=== Pseudostratified Epithelium ===
In this type of simple epithelium the nuclei of the cells appear in irregular layers and may give the false impression that the cells themselves are stratified. In a pseudostratified epithelium all the cells reach the basement membrane even though the nuclei lie at different levels in the tissue. Only the tall cells, however, reach the free surface.

==== Slide 2: Trachea (H&E) ====
On slide 2, Trachea (H&E), identify the pseudostratified columnar ciliated epithelium which lines the lumen of the trachea. Find an area where the epithelium is intact; it is torn off in places. The epithelium rests on a thick basement membrane. Scattered throughout the epithelium are numerous goblet cells that produce a mucous secretion that traps inspired particles. Study the position of the nuclei. Note once again the cilia of the tall cells of the pseudostratified columnar epithelium.

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==== Slide 6: Epididymis (H&E) ====
On slide 6, Epididymis (H&E), is a section through the epididymis, a highly coiled genital duct of the male. The cross and oblique sections of this duct are the most numerous of the tubular structures on this slide. Study the pseudostratified columnar epithelium lining the lumen of the epididymis. Goblet cells and cilia are lacking and the basement membrane is not as prominent as it is for the epithelium of the trachea. Tall columnar cells with stereocilia are present. Smaller basal cells can be identified by observing their nuclei that are located close to the basement membrane.

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== Stratified Epithelium ==
[[File:HistologicChapter3StratifiedSquamousEpithelium.jpg|thumb|200px|Stratified squamous epithelium schematic]]
This type of epithelium has more than one layer of cells present. The epithelium is named according to the shape of the surface cells even though the underlying cells may be a different shape. For example, if the surface cells are squamous, but the underlying cells are cuboidal or columnar, the epithelium is a stratified squamous epithelium.

=== Stratified Squamous Epithelium, Noncornified/Nonkeratinized (Moist) ===
On slide 131, Esophagus (H&E) identify the noncornified/nonkeratinized, stratified squamous epithelium. Note the flattened, nucleated surface cells, the “middle zone” of the polyhedral shaped cells, and the basal layer of the polyhedral shaped cells, and the basal layer of columnar cells which rests on the basement membrane. Characteristically, the lower surface of the epithelium is undulated.

==== Slide 131: Esophagus (H&E) ====
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=== Stratified Squamous Epithelium, Cornified/Keratinized (Dry) ===
On slide 4, Thin skin (H&E) and Slide 46, Thick skin (H&E), study the representative types of cornified/keratinized, stratified squamous epithelium. Note the characteristics of the cells at the various levels. The surface layer of cells, represented by the stratum corneum of the epidermis, lacks nuclei and keratin proteins have replaced the cytoplasm. The surface cells of the skin are constantly desquamated. They are replenished by mitotic divisions occurring in the basal layer of epithelial cells. Note how much thicker the stratum corneum is for thick skin than for thin skin.

==== Slide 4: Thin Skin (H&E) ====
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==== Slide 46: Thick Skin (H&E) ====
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=== Stratified Cuboidal and Stratified Columnar Epithelium ===
On slide 111, Epiglottis (H&E), look in the connective tissue underlying the surface epithelium for ducts of glands lined with stratified cuboidal or stratified columnar epithelium. The surface epithelium of the epiglottis is an intermediate type where a change is being made from stratified squamous to pseudostratified columnar epithelium (some of the surface cells are torn off).

==== Slide 111: Epiglottis (H&E) ====
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=== Transitional Epithelium ===
Transitional epithelium of the urinary passages and bladder shows variations in thickness according to the contracted or dilated state of the structure this epithelium lines. For example, in the contracted urinary bladder, the epithelium may be five or six cell layers thick with the surface cells appearing as large, cuboidal cells that bulge into the lumen. The basal cells are smaller than the surface cells and they interdigitate with the overlying cells. When the bladder fills with urine and becomes distended, the epithelium appears to be only two or three layers thick, and the surface cells are flattened.

On slide 121, Urinary bladder (H&E), identify the transitional epithelium and study its characteristics. Are any of the surface cells binucleated?

==== Slide 121: Urinary Bladder (H&E) ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 3

2014-07-09T19:27:08Z

Seung Park:

== Introduction ==
An epithelium is defined as a tissue that covers or lines the free surfaces of the body. It is one of four fundamental body tissues, with the other three basic tissues being muscle, nervous and connective tissues. Histologically, an epithelium is characterized as being composed of cells sitting upon a basement membrane. The cells are usually arranged in one or more layers with scant intercellular material, or they may sometimes be arranged in cords as in some endocrine glands.

One of the surfaces of an epithelium is exposed either to air or fluid, whereas the other surface is generally attached to a basement membrane that rests upon an underlying connective tissue. With rare exceptions, epithelium is not penetrated by blood vessels and must rely on diffusion processes from the underlying blood supply of the connective tissue for the exchange of nutrients, gases, and wastes (e.g., the endothelial lining of a blood vessel).

Epithelial tissues show numerous specializations of the free surface of cells or of the component cells themselves. For example, the glands of the skin and intestinal tract are derived from epithelium. The embryonic epithelium invaginates into the underlying connective tissue during embryonic development to differentiate into glandular structures. Remember that epithelial tissues are specialized to function in secretion, protection, excretion, absorption, lubrication, sensation, and even reproduction.

One should be able to classify any variety of epithelium according to its structure. An epithelium is usually named according to the appearance of the surface cells. The shape of the cells is important in naming the epithelium. Sometimes the shape referred to is the three dimensional one as in the case of squamous cells (scale-like) and sometimes the two dimensional appearance is referred to as it is seen when the cell is cut vertically to its base. Thus “cuboidal” cells which may appear as squares in sections are actually prismatic in shape with eight sides if seen in their entirety. “Columnar” cells are more elongated prisms. If a cell is surrounded and compressed equally on all sides by other cells, it is usually fourteen sided and appears as a polyhedron in a section.

Identify the following representative varieties of epithelial and be able to interpret the appearance even if it is not cut vertically to the basement membrane.

== Simple Epithelium ==
This type of epithelium has one layer of cells.

=== Simple Squamous Epithelium ===
[[File:HistologicChapter3SimpleSquamousEpithelium.jpg|thumb|200px|Simple squamous epithelium schematic]]
This “pavement epithelium” has flattened scale-like or plate-like cells.

==== Slide 118: Kidney (PASH) ====
On Slide 118, Kidney (PASH) locate the parietal layer of Bowman’s capsule surrounding the glomeruli (blood capillaries). Identify the layer of simple squamous epithelium which forms the parietal layer of Bowman’s capsule. These cells rest on a pink-staining basement membrane. Note that you can see only the nuclei clearly; the attenuated cytoplasm is indistinct.

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==== Slide 18: Spleen (H&E) ====
On slide 18, Spleen (H&E), locate the connective tissue capsule that covers the spleen and note the simple squamous epithelium covering the capsule. This lining is called the mesothelium. A mesothelium is defined as a single layer of flattened cells forming an epithelium that lines serous (body) cavities. Note the shapes of the cells. In some regions, they may appear to be slightly cuboidal.

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=== Simple Cuboidal Epithelium ===
[[File:HistologicChapter3SimpleCuboidalEpithelium.jpg|thumb|200px|Simple cuboidal epithelium schematic]]
In this kind of epthelium, the height of each component cell is approximately equivalent to its width.

==== Slide 114: Kidney (H&E) ====
On slide 114, Kidney (H&E), locate segments of kidney tubules lined with simple cuboidal epithelium. In this type of epithelium the nucleus is round and located in the center of the cell. Other segments of a kidney tubule may be lined by epithelial cells ranging from simple squamous to low columnar or pyramidal (modified columnar) in shape. On slide 118, Kidney (PASH) note how well the PAS stain demonstrates the basement membranes underlying the various epithelial. Cells of different heights are also readily observed on this slide.

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=== Simple Columnar Epithelium ===
[[File:HistologicChapter3SimpleColumnarEpithelium.jpg|thumb|200px|Simple columnar epithelium schematic]]
In this kind of epithelium, the height exceeds the width of the cell.

==== Slide 140: Duodenum (PASH) ====
On slide 140, duodenum, (PASH), observe the layer of columnar cells that cover the villi. The ovoid nuclei are located in the lower one-half of the cells. Study the shapes of the cells, the location of the nuclei and the specialization of the free surface. These columnar cells are absorptive cells that have microvilli forming a striated border and covered by a PAS-positive glycocalyx. Goblet cells, which are columnar cells modified to secrete mucus, can be seen interspersed among the absorptive columnar epithelial cells. The goblets in these cells exhibit heavy PAS staining.

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=== Pseudostratified Epithelium ===
In this type of simple epithelium the nuclei of the cells appear in irregular layers and may give the false impression that the cells themselves are stratified. In a pseudostratified epithelium all the cells reach the basement membrane even though the nuclei lie at different levels in the tissue. Only the tall cells, however, reach the free surface.

==== Slide 2: Trachea (H&E) ====
On slide 2, Trachea (H&E), identify the pseudostratified columnar ciliated epithelium which lines the lumen of the trachea. Find an area where the epithelium is intact; it is torn off in places. The epithelium rests on a thick basement membrane. Scattered throughout the epithelium are numerous goblet cells that produce a mucous secretion that traps inspired particles. Study the position of the nuclei. Note once again the cilia of the tall cells of the pseudostratified columnar epithelium.

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==== Slide 6: Epididymis (H&E) ====
On slide 6, Epididymis (H&E), is a section through the epididymis, a highly coiled genital duct of the male. The cross and oblique sections of this duct are the most numerous of the tubular structures on this slide. Study the pseudostratified columnar epithelium lining the lumen of the epididymis. Goblet cells and cilia are lacking and the basement membrane is not as prominent as it is for the epithelium of the trachea. Tall columnar cells with stereocilia are present. Smaller basal cells can be identified by observing their nuclei that are located close to the basement membrane.

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== Stratified Epithelium ==
[[File:HistologicChapter3StratifiedSquamousEpithelium.jpg|thumb|200px|Stratified squamous epithelium schematic]]
This type of epithelium has more than one layer of cells present. The epithelium is named according to the shape of the surface cells even though the underlying cells may be a different shape. For example, if the surface cells are squamous, but the underlying cells are cuboidal or columnar, the epithelium is a stratified squamous epithelium.

=== Stratified Squamous Epithelium, Noncornified/Nonkeratinized (Moist) ===
On slide 131, Esophagus (H&E) identify the noncornified/nonkeratinized, stratified squamous epithelium. Note the flattened, nucleated surface cells, the “middle zone” of the polyhedral shaped cells, and the basal layer of the polyhedral shaped cells, and the basal layer of columnar cells which rests on the basement membrane. Characteristically, the lower surface of the epithelium is undulated.

==== Slide 131: Esophagus ====
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=== Stratified Squamous Epithelium, Cornified/Keratinized (Dry) ===
On slide 4, Thin skin (H&E) and Slide 46, Thick skin (H&E), study the representative types of cornified/keratinized, stratified squamous epithelium. Note the characteristics of the cells at the various levels. The surface layer of cells, represented by the stratum corneum of the epidermis, lacks nuclei and keratin proteins have replaced the cytoplasm. The surface cells of the skin are constantly desquamated. They are replenished by mitotic divisions occurring in the basal layer of epithelial cells. Note how much thicker the stratum corneum is for thick skin than for thin skin.

==== Slide 4: Thin Skin ====
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==== Slide 46: Thick Skin ====
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=== Stratified Cuboidal and Stratified Columnar Epithelium ===
On slide 111, Epiglottis (H&E), look in the connective tissue underlying the surface epithelium for ducts of glands lined with stratified cuboidal or stratified columnar epithelium. The surface epithelium of the epiglottis is an intermediate type where a change is being made from stratified squamous to pseudostratified columnar epithelium (some of the surface cells are torn off).

==== Slide 111: Epiglottis ====
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=== Transitional Epithelium ===
Transitional epithelium of the urinary passages and bladder shows variations in thickness according to the contracted or dilated state of the structure this epithelium lines. For example, in the contracted urinary bladder, the epithelium may be five or six cell layers thick with the surface cells appearing as large, cuboidal cells that bulge into the lumen. The basal cells are smaller than the surface cells and they interdigitate with the overlying cells. When the bladder fills with urine and becomes distended, the epithelium appears to be only two or three layers thick, and the surface cells are flattened.

On slide 121, Urinary bladder (H&E), identify the transitional epithelium and study its characteristics. Are any of the surface cells binucleated?

==== Slide 121: Urinary Bladder (H&E) ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 5

2014-07-09T19:25:21Z

Seung Park:

== Introduction ==

Muscle, one of the four basic tissues, is highly specialized for contractility. The fundamental unit of muscle is the muscle cell (usually called a muscle fiber or just “fiber”) which shortens in its long axis upon stimulation. The contraction occurs when two types of filaments, actin and myosin, interact with each other to interdigitate, thus pulling the two ends of the fibers closer together. The three kinds of muscle are smooth muscle, skeletal muscle, and cardiac muscle. The latter two are called striated muscle because of microscopically visible cross striations exhibited by the fibers. Smooth muscle lacks cross striations.

== Smooth Muscle ==

=== Slide 31: Ileum ===

On slide 31, Ileum (H&E), identify smooth muscle fibers in the relatively thick muscle coat (muscularis). The muscle fibers are arranged in two well-defined layers: An inner circular and an outer longitudinal. Between the two layers of muscle is a thin layer of connective tissue that varies in thickness and contains a plexus of nerve fibers and also parasympathetic ganglion cells known as the myenteric plexus (of Auerbach).

In the outer muscle layer, where the smooth muscle fibers are cut in longitudinal section, observe the shape of the smooth muscle cell (fiber), its size, the amount of sarcoplasm, and the position of the nucleus. Note the elongated shape of the smooth muscle nuclei as compared to nearby fibroblast nuclei in the connective tissue septa. With medium power, scan this outer muscular layer and notice how the smooth muscle is arranged in the form of broad sheets or bands.

Now look at the inner muscle layer where the smooth muscle fibers are cut transversely. Observe that the nucleus is not always seen. Why? When it is seen, notice how it varies in size in relation to the diameter of the fiber. Note especially the position of the nucleus within the fiber.

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=== Slide 121: Urinary Bladder ===

On slide 121, Urinary bladder (H&E), notice how the smooth muscle fibers of the thick muscle coat are arranged as interlacing bundles. Each bundle is supported by moderately dense connective tissue. The arrangement increases the efficiency of expelling urine quickly as well as increases the ability of the organ to withstand the force of distension as urine accumulates within the bladder.

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== Skeletal Muscle ==
[[File:HistologicChapter5SkeletalMuscle.jpg|thumb|200px|Skeletal Muscle Diagram]]

=== Slide 20: Skeletal Muscle ===

On slide 20, Skeletal muscle (H&E), is one of the muscles in the larynx whose fibers appear more loosely arranged because of edema in the connective tissues; therefore, individual fibers can be seen more easily. The muscle fibers are sectioned in various planes. Keep in mind the large size (diameter) of skeletal muscle fibers as compared with smooth muscle fibers.

Look at the muscle fibers in longitudinal section. Note: The fibers are long and approximately uniform in diameter; cross-striations are visible varying in distinctness in different fibers; fibers are multinucleated with nuclei at the periphery of the fiber; a thin sarcolemma (plasmalemma) covers the fibers.

Select a well-stained longitudinal fiber in which cross-striations are readily visible with low power (10 x). Study the striations. At 40 x power the dark A bands and the light I bands can be distinguished, and the thin Z line in the I band can sometimes be seen.
While the A band remains constant in width, the I band width varies according to the state of contraction: Very narrow if muscle was contracted at time of fixation, or wider if muscle was fixed in a relaxed or post-contraction state. An additional band, the H band (a lighter area within the A band) is rarely visible with the light microscope. The segment between two Z-lines is a sarcomere - the function unit of all striated muscle (skeletal and cardiac). With H&E, the Z-lines appear as fine red lines.

In cross section, note the uniform diameter of the fibers and the peripherally located nuclei. In a good cross section, the myofibrils appear as pinpoints. Oblique sections are neither cross nor longitudinal and characteristics are not always well demonstrated.
Note the fine loose connective tissue between muscle fibrils (endomysium). It is easily seen here.

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=== Slide 8: Intervertebral Disc ===

Slide 8, Intervertebral disc (H&E). Some of the deep back muscle fibers attach directly to the periosteum by means of short tendons or by an apparent continuity between muscle and the connective tissue of the periosteum.

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== Cardiac Muscle ==

=== Slide 75: Heart and Purkinje Fibers ===

Slide 75, Heart and Purkinje fibers (H&E), shows a portion of the left ventricle with its epicardium and endocardium, the aorta, coronary artery and vein. Purkinje fibers are present in the subendocardial areas. This slide demonstrates the major characteristics of cardiac muscle tissue: branching myocardial fibers, cross-striations, intercalated discs, and a centrally placed nucleus within each muscle fiber.

Myocardial fibers are seen cut longitudinally, obliquely, and transversely. The reason for this orientation is that the muscle fibers of the heart course spirally within the walls of the heart. The spiral arrangement permits efficient filling and expulsion of the blood. In longitudinal sections of muscle observe: the cross-striations of the fibers; size, shape, and location of the nucleus, the clear area at either end of the nucleus and the myofibrils within the sarcoplasm. Note how the intercalated discs (darkly stained lines) extend either straight across the fiber or in step-wise fashion.

Between the myocardial fibers is seen loose connective tissue of the endomysium containing numerous capillaries. The rich vascularity of heart muscle is emphasized.

Locate the lower right-hand part of the large section (interventricular septum) on low power. The thin tissue covering most of the upper and lower margins of the section is endocardium. The endocardium includes the single layer of endothelial cells plus underlying connective tissue With medium and high power find the Purkinje fibers immediately adjacent to the upper and lower endocardium. The latter are modified cardiac fibers specialized to conduct impulses and form part of the impulse-conducting system of the heart. Purkinje fibers are lighter-stained (H&E), contain fewer myofibrils (in cross-section the myofibrils are found to be limited to the periphery of the fiber), and have more sarcoplasmic space surrounding each nucleus than is the case for regular myocardial fibers. Nuclei are more rounded but often appear irregular in outline. Look for longitudinal and cross-sections of the Purkinje fibers.

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=== Slide 91: Cardiac Muscle ===

On slide 91, Cardiac muscle (Gomori’s), the cross-striations of the myocardial fibers and the intercalated discs are more prominently displayed. The intercalated discs stain as a black line. Between the myocardial fibers the capillaries and other vessels are readily seen; the black bodies within the vessels are primarily erythrocytes. Note the strands of blue-staining connective tissue which accompany the blood vessels and which also comprise part of the endocardium and epicardium. See sketch on next page for location of Purkinje fibers.

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 4

2014-07-09T19:24:12Z

Seung Park:

== Loose Connective Tissue ==

=== Slide 94: Loose Connective Tissue in the colon (H&E) ===

At low power locate the zone of loose connective tissue that lies between the layer of glands and the thick layer of dense, eosinophilic smooth muscle. Many small blood vessels lined with simple squamous epithelium (endothelium) are present in the connective tissue.

With higher power, select a good area of loose tissue and note:
* Collagenous fibers are of various sizes, stained pink with eosin, are coursing in various directions, and are cut in various planes. They appear ragged in sections.
* Fine elastic fibers are present but difficult to distinguish with this stain, also because sectioning will leave only fragments of fibers. Look for some. They will be fine, homogenous threads, poorly stained but somewhat refractile.
* Fibroblasts are shrunken; this is typical in routinely prepared sections. Nuclei are clearly defined and stain darkly. Thin cell processes may be seen on some cells. Other cell types are rare.

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=== Slide 20: Skeletal Muscle and Loose Connective Tissue (H&E) ===

This is a section through one of the muscles of the larynx. Much of the associated connective tissue is very loose because of edema (a complication here because of a skull fracture); the fibers are spread far apart and excessive numbers of cells are present.

Look in the zone of loose connective tissue in the part of the section just beneath the epithelial layer. Note that the fibers course in various directions. Some of the thinnest fibers seen here are probable reticular fibers.

Identify fibroblasts, numerous lymphocytes, and plasma cells.

Look in the small areas of more normal loose connective tissue, nearer the muscle and elsewhere; identify collagenous and elastic fibers.

This slide has groups of mixed glands with a special epithelium that need not be identified, but their ducts may be lined with simple columnar or stratified columnar epithelium.

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=== Slide 28: Loose Connective Tissue With Mast Cells ===

This is abdominal skin from a 3-week old rat, fixed to preserve mast cell granules, stained with toluidine blue (no counter stain).

The surface of the skin is thin stratified squamous epithelium, the subcutaneous connective tissue is young, loose connective tissue.

Identify fibroblasts and thin collagenous fibers (stained very faintly).

Mast cells are abundant. Find some that show the entire cell: oval cell body, cytoplasm filled with purple granules (some may appear vacuolated), and a central small rounded light blue nucleus. Note the large size of the mast cells.

The epithelial-lined structures extending in from the surface epithelium are developing hair follicles.

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=== Slide 144: Colon (PASH) ===

Mast cells are demonstrable in this section of the colon. Look in the deepest part of the layer of glands. They are large oval cells with a small central nucleus and cytoplasm densely packed with prominent PAS-positive granules.

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=== Slide 100: Macrophages Ingesting Trypan Blue ===

Trypan blue, a “vital” dye, is used to demonstrate phagocytic activity of macrophages. A 0.5% solution was injected intraperitoneally into young rats on alternate days for two weeks. Macrophages all over the body ingest the trypan blue particles.

Slide 100, Mesentery and mesenteric lymph nodes, azocarmine. All nuclei stain pinkish-red with azocarmine; other tissues take only a faint background stain.

Look in the connective tissue of the mesentery for macrophages of various sizes with inclusions of trypan blue in their cytoplasm.

The lymph nodes are dense masses of lymphocytes supported in a reticular connective tissue stroma. Look for macrophages in the less dense areas.

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== Dense Connective Tissue ==

=== Slide 3: Dense Irregular Connective Tissue in Scalp (H&E) ===

A thick layer of dense irregular connective tissue underlies the stratified epithelium. Prominent structures seen in this layer are hair follicles, sebaceous glands, and sweat glands. Also present are small blood vessels and scattered fat cells.

Study the connective tissue. Note:
* The density of the connective tissue layer.
* The thick bundles of collagenous fibers, seen in various planes of section - cross, oblique and longitudinal sections.
* Look for thin, refractile elastic fibers. They can be seen with high power and careful focusing.
* Identify fibroblasts. Nuclei are seen, little or no cytoplasm.

Review the structure of stratified squamous epithelium. The eosinophilic, “stringy material” in the uppermost part of the epithelium is the stratum corneum that is sloughing.

The thick wall of the hair follicles is a somewhat modified stratified squamous epithelium continuous with the surface epithelium.

Sebaceous glands, associated with the hair follicles, are composed mainly of rounded cells filled with oily secretion which dissolves in prepared sections, thus leaving vacuolated cells that stain very lightly. The nucleus is centrally placed.

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== Adipose Tissue ==

=== Slide 46: Adipose Tissue in Thick Skin (H&E) ===

Fat is found in the subcutaneous tissue, below the layer of dense irregular connective tissue. It is present largely as adipose tissue.

Scan to locate the adipose tissue.

Recognize fat cells as large, clear cells.

In the larger masses of cells, note connective tissue septa, which form lobules of adipose tissue.

With higher magnifications:

Look at the large, more or less rounded individual fat cells, empty, showing the cell membrane and perhaps some of the rim of cytoplasm. (Fat has been removed during preparation.)

Look for an eccentric nucleus within the fat cell. Every cell will not show one.
Nuclei of fibroblasts are present between fat cells. It is not always easy to distinguish these from fat cell nuclei.

Look at the interlobular septa. What type of connective tissue forms these septa?

Recognize blood vessels in the septa and smaller vessels among the fat cells.

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Look also at slide 3 (scalp) and slide 75 (heart). Locate the areas of adipose tissue and note features as above.

==== Slide 3: Scalp ====

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==== Slide 75: Heart ====

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{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 2

2014-07-08T22:06:00Z

Seung Park: /* Mitosis */

== Cells, Organelles, and Inclusions ==
[[File:HistologicChapter2Cell.jpg|thumb|200px|Cell schematic]]
To begin the study of cellular structure, you are asked to identify several kinds of cells, cellular specializations and inclusions of cells. Learn to distinguish between the nucleolus, the nucleus, and the cytoplasm of a cell. Observe the appearance of the chromatin, the position of the nucleus within the cell and the staining characteristics of the cytoplasm. Note the size of the cells, the density of similar cells, and their arrangement in the tissue. As you study the different cell types, keep in mind that sectioned material is being observed and that the appearance of the cell may vary depending on the plane of section.

A cell usually contains only one nucleus, but some cells may be binucleate. The nucleus often conforms to the shape of the cell being spherical, ovoid, or elongated. Other nuclei may be crescent shaped or lobated. It can be flattened towards the base of the cell when the pressure from cytoplasmic constituents “pushes it” there. Nucleoli may or may not be present. In sectioned material, the nucleus or nucleolus may appear to be absent from a cell because they were not in the plane of sectioning. If the cell is in a phase of mitosis, the nucleus will appear different from nuclei of other non-mitotic cells of the tissue.

The cytoplasm often exhibits modifications according to the specific functions of the cell or the tissue. Muscle cells have contractile myofibrils. Secretory cells of the salivary glands possess numerous secretory granules. Epithelial cells of the skin produce a protein called keratin for protection. The epithelial lining of the respiratory tract may possess cilia. White blood cells may contain primary and specific granules. Neurons possess neurofibrils, etc. The list is almost endless.

NOTE: The objective of this first exercise is merely to gain an awareness of the varieties of cell sizes, cell shapes, cell types, cell staining characteristics and cell organelles or inclusions. You are not expected, at this time, to become familiar with the over-all structure of the tissues and organs where these cells are located.

=== Microscopic Study: Architecture ===
==== Slide 25: Spinal Cord ====
On slide 25, Spinal Cord (Thionin) find under low power the cell bodies of multipolar neurons located in the two anterior horns of the gray matter (if the slide is held towards the light, the gray matter appears H-shaped). With medium power, identify a cell body containing a large pale nucleus and a darkly stained nucleolus. Study this cell under high power. The irregular, granular-like, basophilic staining masses within the cytoplasm are called Nissl bodies. They consist of free ribosomes and granular endoplasmic reticulum.

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==== Slide 73: Spinal Ganglion ====
On slide 73, Spinal Ganglion (silver) identify the large cell bodies of the ganglion cells associated with the sensory root of spinal nerves. The cell bodies of these unipolar neurons range in size from 15μm to 100μm. Compare a number of ganglion cell bodies for size differences. The centrally located nuclei stain palely and appear as clear spaces in the middle of the granular cytoplasm. With careful observation you will see nuclei of much smaller cells immediately surrounding the cell bodies of the ganglion cells. These represent satellite cells. Note how much smaller they are than the nuclei of the ganglion cells.

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==== Slide 149: Liver ====
On slide 149, Liver (H&E) observe that the hepatocytes (liver parenchymal cells) appear to be arranged as rows or cords of cells. Actually the tridimensional arrangement of these cells is in cellular sheets or plates which are separated by blood-filled spaces called sinusoids. Red blood corpuscles may be seen in some of the sinusoids. Note that cell boundaries can be distinctly seen between many of the liver cells. The polyhedral- shaped hepatocytes have round, centrally located nuclei containing one or more nucleoli and scattered clumps of chromatin. Binucleated hepatocytes can be found. Note the granularity of the eosinophilic staining cytoplasm

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==== Slide 154: Pancreas ====
Slide 154, Pancreas (H&E) has cells which distinctly exhibit a difference between basophilic regions and acidophilic regions. After studying the cells with medium power, turn to high power to complete your study. Observe that the cell boundaries are indistinct. Note that the cytoplasm in the basal region of the acinar cells is basophilic. Here the ribonucleoproteins associated with rough endoplasmic reticulum and the large numbers of mitochondria are sufficiently dense to stain with the basic dye. Note, however, the red staining of the apical half of the acinar cells. This acidophilic staining cytoplasm contains numerous secretory granules that stain brightly with the eosin stain. The nuclei are basophilic staining as are the nuclei of all cells. Observe that the nuclei are characteristically located in the basal one-third of the cell. Nucleoli may be seen in many cells.

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=== Microscopic Study: Cell Types ===
==== Slide 2: Trachea ====
[[File:HistologicChapter2Cilia.jpg|thumb|200px|Cilia schematic]]
On slide 2, Trachea (H &E) identify the cilia on the tall cells of the pseudostratified columnar epithelium that line the lumen of the trachea. Each cilium is derived from a basal body, represented here in aggregate by the dark lines where the cilia attach to the cell. In some regions of this tissue the cilia are absent or the entire epithelium is missing. This is artifact.

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==== Slide 89: Skeletal Muscle ====
On slide 89, Skeletal Muscle (H&E) identify muscle fibers cut in longitudinal section. Under high power note the striated appearance of the muscle cells. Although not readily visible, the cytoplasm of these cells contains myofibrils, the contractile elements of the cell. The arrangement of these myofibrils and their subunits, the myofilaments, impart the striated appearance to the muscle fibers.

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==== Slide 31: Ileum ====
On slide 31, Ileum (H &E) identify with low power the villi projecting from one side of the tissue. With high power identify the tall cells (simple columnar cells) which cover these villi. On the free surface of these cells can be seen a dense line representing the striated border. This border consists of cytoplasmic processes termed microvilli that greatly increase the absorptive area of the small intestine. In light microscopy, the microvilli appear vertically striated so these projections form a “striated border.”

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== Mitosis ==
[[File:HistologicChapter2Mitosis.jpg|thumb|200px|Mitosis schematic]]
Mitosis can be viewed as the means whereby identical genetic material, contained in the chromosomes, is distributed to two daughter nuclei. It can be divided into four stages, each characterized by certain features of nuclear or chromosome morphology and chromosome movement. The stages are arbitrary in that mitosis is a continuous process from its inception at prophase through the stages of metaphase and anaphase to the final stage of telophase. The nucleus of a cell that is not dividing is in the interphase stage.

The number of mitotic figures in a tissue is an index of the rate of turnover of the component cells. In benign tumors, mitotic figures are few in numbers, whereas in malignant tumors, mitotic figures are more numerous and may include many bizarre forms. Hence, the recognition of mitotic figures is one criterion for the interpretation of various kinds of pathology of a tissue.

=== Microscopic Study: Mitosis ===
On slide 34, Mitosis (Iron H), are longitudinal sections of onion root tips in which cells have been fixed in various stages of mitosis. Learn to identify the characteristic arrangement of the chromatin in each state.

==== Slide 34: Mitosis ====
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{{Template:Histologic}}

[[Category:Histologic]]

Histologic

2014-07-08T22:05:02Z

Seung Park:

Welcome to [[Histologic]], a constantly-updated, wiki-based comprehensive manual for the teaching of histology at the [http://www.uab.edu/medicine/home/ University of Alabama at Birmingham School of Medicine]. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. For usage instructions, please see [[Histologic:Chapter 1|Chapter 1]]. To get in touch with us, please see [[Histologic:Contributors|Contributors]].

== [[Histologic:Chapter 1|Chapter 1: Overview]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Contributors|Contributors]] ==
* [[Histologic:Contributors#Acknowledgements|Acknowledgements]]
* [[Histologic:Contributors#Staff|Staff]]

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-08T22:04:12Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00002</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-08T22:03:17Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top left, there is a toolbar. Magnification level can also be adjusted using the + and - buttons on the toolbar. The rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00002</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-08T22:01:40Z

Seung Park:

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. Magnification level can also be adjusted using the appropriate buttons on the toolbar on the top left; the rightmost button on the toolbar toggles fullscreen mode. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00002</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Template:Histologic

2014-07-08T21:48:55Z

Seung Park:

{{Navbox
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|title = [[Histologic]]
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[[Histologic]]
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* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]
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* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
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* [[Histologic:Chapter 8#Introduction|Introduction]]
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* [[Histologic:Chapter 9#Introduction|Introduction]]
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* [[Histologic:Chapter 10#Introduction|Introduction]]
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* [[Histologic:Chapter 11#Introduction|Introduction]]
|group12 = [[Histologic:Chapter 12|Chapter 12]]
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* [[Histologic:Chapter 12#Introduction|Introduction]]
|group13 = [[Histologic:Chapter 13|Chapter 13]]
|list13 =
* [[Histologic:Chapter 13#Introduction|Introduction]]
|group14 = [[Histologic:Chapter 14|Chapter 14]]
|list14 =
* [[Histologic:Chapter 14#Introduction|Introduction]]
|group15 = [[Histologic:Chapter 15|Chapter 15]]
|list15 =
* [[Histologic:Chapter 15#Introduction|Introduction]]
|group16 = [[Histologic:Chapter 16|Chapter 16]]
|list16 =
* [[Histologic:Chapter 16#Introduction|Introduction]]
|group17 = [[Histologic:Chapter 17|Chapter 17]]
|list17 =
* [[Histologic:Chapter 17#Introduction|Introduction]]
|group18 = [[Histologic:Chapter 18|Chapter 18]]
|list18 =
* [[Histologic:Chapter 18#Introduction|Introduction]]
|group19 = [[Histologic:Chapter 19|Chapter 19]]
|list19 =
* [[Histologic:Chapter 19#Introduction|Introduction]]
|group20 = [[Histologic:Contributors|Contributors]]
|list20 =
* [[Histologic:Contributors#Acknowledgements|Acknowledgements]]
* [[Histologic:Contributors#Staff|Staff]]

}}<noinclude>

[[Category:Histologic Templates]]
[[Category:Histologic]]
</noinclude>

Histologic:Contributors

2014-07-08T21:48:25Z

Seung Park: Seung Park moved page Histologic:Acknowledgements and Staff to Histologic:Contributors without leaving a redirect

== Acknowledgements ==
This Virtual Microscopy Histology Laboratory Manual is a derivative work from the laboratory teaching materials produced over many years by anatomists from the University of Alabama at Birmingham School of Medicine. The instructors who designed the curriculum, acquired the teaching slide sets and developed this laboratory manual were: George Hand, PhD, Jim Sheetz, PhD and Laura Cotlin, PhD

The virtual microscopy slides described in this manual are primarily scans of original glass slides used in the University of Alabama at Birmingham School of Medicine Cell Biology and Histology teaching program. Additional virtual microscopy slides were kindly contributed by: James L. Fishback, MD, University of Kansas School of Medicine; Mary Ann Sens, MD, PhD, University of North Dakota School of Medicine; and Richard M. Conran, MD, PhD, Uniformed Services University of the Health Sciences.

== Staff ==
=== Faculty Advisors ===
==== Molecular and Cellular Pathology ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=19493 Peter G. Anderson, DVM, PhD]

==== Pathology Informatics ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=61255 Seung Park, MD]

=== Residents, Fellows, and Students ===

==== Summer 2014 ====
* [http://bsc.ua.edu/undergraduate-studies/majors/ Matthew Anderson]
* [http://www.uab.edu/medicine/mstp/current-students Tim Kennell, BS]
* [http://www.uab.edu/medicine/pathology/residency-program/current-residents Alexander Feldman, MD]

{{Template:Histologic}}

[[Category:Histologic]]

Histologic

2014-07-08T21:48:05Z

Seung Park: /* Acknowledgements and Staff */

Welcome to [[Histologic]], a constantly-updated, wiki-based comprehensive manual for the teaching of histology at the [http://www.uab.edu/medicine/home/ University of Alabama at Birmingham School of Medicine]. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. For usage instructions, please see [[Histologic:Chapter 1|Chapter 1]]. To get in touch with us, please see [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]].

== [[Histologic:Chapter 1|Chapter 1: Overview]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Contributors|Contributors]] ==
* [[Histologic:Contributors#Acknowledgements|Acknowledgements]]
* [[Histologic:Contributors#Staff|Staff]]

[[Category:Histologic]]

Template:Histologic

2014-07-08T21:46:03Z

Seung Park:

{{Navbox
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|title = [[Histologic]]
|bodyclass = hlist
[[Histologic]]
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* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]
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* [[Histologic:Chapter 2#Mitosis|Mitosis]]
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* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]
|group4 = [[Histologic:Chapter 4|Chapter 4]]
|list4 =
* [[Histologic:Chapter 4#Introduction|Introduction]]
|group5 = [[Histologic:Chapter 5|Chapter 5]]
|list5 =
* [[Histologic:Chapter 5#Introduction|Introduction]]
|group6 = [[Histologic:Chapter 6|Chapter 6]]
|list6 =
* [[Histologic:Chapter 6#Introduction|Introduction]]
|group7 = [[Histologic:Chapter 7|Chapter 7]]
|list7 =
* [[Histologic:Chapter 7#Introduction|Introduction]]
|group8 = [[Histologic:Chapter 8|Chapter 8]]
|list8 =
* [[Histologic:Chapter 8#Introduction|Introduction]]
|group9 = [[Histologic:Chapter 9|Chapter 9]]
|list9 =
* [[Histologic:Chapter 9#Introduction|Introduction]]
|group10 = [[Histologic:Chapter 10|Chapter 10]]
|list10 =
* [[Histologic:Chapter 10#Introduction|Introduction]]
|group11 = [[Histologic:Chapter 11|Chapter 11]]
|list11 =
* [[Histologic:Chapter 11#Introduction|Introduction]]
|group12 = [[Histologic:Chapter 12|Chapter 12]]
|list12 =
* [[Histologic:Chapter 12#Introduction|Introduction]]
|group13 = [[Histologic:Chapter 13|Chapter 13]]
|list13 =
* [[Histologic:Chapter 13#Introduction|Introduction]]
|group14 = [[Histologic:Chapter 14|Chapter 14]]
|list14 =
* [[Histologic:Chapter 14#Introduction|Introduction]]
|group15 = [[Histologic:Chapter 15|Chapter 15]]
|list15 =
* [[Histologic:Chapter 15#Introduction|Introduction]]
|group16 = [[Histologic:Chapter 16|Chapter 16]]
|list16 =
* [[Histologic:Chapter 16#Introduction|Introduction]]
|group17 = [[Histologic:Chapter 17|Chapter 17]]
|list17 =
* [[Histologic:Chapter 17#Introduction|Introduction]]
|group18 = [[Histologic:Chapter 18|Chapter 18]]
|list18 =
* [[Histologic:Chapter 18#Introduction|Introduction]]
|group19 = [[Histologic:Chapter 19|Chapter 19]]
|list19 =
* [[Histologic:Chapter 19#Introduction|Introduction]]
|group20 = [[Histologic:Acknowledgements and Staff|Contributors]]
|list20 =
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

}}<noinclude>

[[Category:Histologic Templates]]
[[Category:Histologic]]
</noinclude>

Histologic:Chapter 1

2014-07-08T20:58:41Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes. Finally, there is a navigational toolbox at the bottom of every page; from there, you can navigate to other chapters and chapter subheadings.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00278</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic

2014-07-08T20:55:27Z

Seung Park:

Welcome to [[Histologic]], a constantly-updated, wiki-based comprehensive manual for the teaching of histology at the [http://www.uab.edu/medicine/home/ University of Alabama at Birmingham School of Medicine]. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. For usage instructions, please see [[Histologic:Chapter 1|Chapter 1]]. To get in touch with us, please see [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]].

== [[Histologic:Chapter 1|Chapter 1: Overview]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]] ==
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

[[Category:Histologic]]

Histologic

2014-07-08T20:52:43Z

Seung Park: /* Chapter 1: Histology */

== [[Histologic:Chapter 1|Chapter 1: Overview]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]] ==
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

[[Category:Histologic]]

Histologic:Chapter 1

2014-07-08T20:50:59Z

Seung Park: /* Using Histologic */

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes.

=== Still Image Example ===
[[File:HistologicChapter2Cell.jpg|thumb|200px|Still image example]]
To the right is a still image example thumbnail that you can click to enlarge.

=== Whole Slide Imaging Example ===
Below is a whole slide imaging example with which you can interact.

<peir-vm>UAB-Histology-00278</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic

2014-07-08T20:48:20Z

Seung Park:

== [[Histologic:Chapter 1|Chapter 1: Histology ]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]] ==
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

[[Category:Histologic]]

Template:Histologic

2014-07-08T20:47:54Z

Seung Park:

{{Navbox
|name = Histologic
|title = [[Histologic]]
|bodyclass = hlist
[[Histologic]]
|group1 = [[Histologic:Chapter 1|Chapter 1]]
|list1 =
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]
* [[Histologic:Chapter 1#Using_Histologic|Using Histologic]]
|group2 = [[Histologic:Chapter 2|Chapter 2]]
|list2 =
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]
|group3 = [[Histologic:Chapter 3|Chapter 3]]
|list3 =
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]
|group4 = [[Histologic:Chapter 4|Chapter 4]]
|list4 =
* [[Histologic:Chapter 4#Introduction|Introduction]]
|group5 = [[Histologic:Chapter 5|Chapter 5]]
|list5 =
* [[Histologic:Chapter 5#Introduction|Introduction]]
|group6 = [[Histologic:Chapter 6|Chapter 6]]
|list6 =
* [[Histologic:Chapter 6#Introduction|Introduction]]
|group7 = [[Histologic:Chapter 7|Chapter 7]]
|list7 =
* [[Histologic:Chapter 7#Introduction|Introduction]]
|group8 = [[Histologic:Chapter 8|Chapter 8]]
|list8 =
* [[Histologic:Chapter 8#Introduction|Introduction]]
|group9 = [[Histologic:Chapter 9|Chapter 9]]
|list9 =
* [[Histologic:Chapter 9#Introduction|Introduction]]
|group10 = [[Histologic:Chapter 10|Chapter 10]]
|list10 =
* [[Histologic:Chapter 10#Introduction|Introduction]]
|group11 = [[Histologic:Chapter 11|Chapter 11]]
|list11 =
* [[Histologic:Chapter 11#Introduction|Introduction]]
|group12 = [[Histologic:Chapter 12|Chapter 12]]
|list12 =
* [[Histologic:Chapter 12#Introduction|Introduction]]
|group13 = [[Histologic:Chapter 13|Chapter 13]]
|list13 =
* [[Histologic:Chapter 13#Introduction|Introduction]]
|group14 = [[Histologic:Chapter 14|Chapter 14]]
|list14 =
* [[Histologic:Chapter 14#Introduction|Introduction]]
|group15 = [[Histologic:Chapter 15|Chapter 15]]
|list15 =
* [[Histologic:Chapter 15#Introduction|Introduction]]
|group16 = [[Histologic:Chapter 16|Chapter 16]]
|list16 =
* [[Histologic:Chapter 16#Introduction|Introduction]]
|group17 = [[Histologic:Chapter 17|Chapter 17]]
|list17 =
* [[Histologic:Chapter 17#Introduction|Introduction]]
|group18 = [[Histologic:Chapter 18|Chapter 18]]
|list18 =
* [[Histologic:Chapter 18#Introduction|Introduction]]
|group19 = [[Histologic:Chapter 19|Chapter 19]]
|list19 =
* [[Histologic:Chapter 19#Introduction|Introduction]]
|group20 = [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]]
|list20 =
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

}}<noinclude>

[[Category:Histologic Templates]]
[[Category:Histologic]]
</noinclude>

Histologic:Chapter 1

2014-07-08T20:47:23Z

Seung Park:

== Introduction ==
Histology is the study of the microscopic structure of biological material and the ways in which individual components are structurally and functionally related. It is central to medical science since it stands at the crossroads between biochemistry, molecular biology and physiology on the one side, and pathologic processes that cause disease on the other. Although often thought of as an archaic discipline, practical knowledge of histology is in actuality an integral part of modern investigative techniques and current medical practice

In this laboratory manual we will focus on the basic structure of human tissues. We will concentrate on structure-function correlations that are important in the understanding of disease processes. Thus, we will not attempt to provide a comprehensive review of all structures in the body; instead we will focus just on the structural relationships that are integral to disease.

Almost all of the tissues we will review are human tissues obtained at autopsy or from surgical biopsies. As a general rule all fresh tissues are fixed in 10% neutral buffered formalin and are embedded in paraffin wax before cutting microscopic tissue sections. The embedding process requires dehydration of the tissues using organic solvents, permeation of the tissues with paraffin wax, and hardening of the wax for cutting. Tissue sections are then cut at 5 to 7 microns in thickness and placed on glass slides. The tissues are then rehydrated and stained. This dehydration-wax embedding - rehydration cycle results in dissolution of any lipid materials within the tissues. This may lead to alterations in the morphology of tissues. However, if you understand the process you can overlook these artifacts and still make accurate assessments of the tissue. One classic “artifact” is the loss of fat from liver tissue obtained from a patient with fatty liver. This leaves holes in the tissue where the fat globules had been situated before they were dissolved away. These and other classic artifacts will become second nature to you as you review tissue sections.

== Overview of Tissue Preparation and Staining for Microscopy ==
# '''Obtaining tissues''' - Human material is obtained at autopsy or from surgical biopsies.
# '''Fixation''' - To preserve the tissue, it is placed immediately in a fixative which acts to preserve the cell and tissue constituents in as lifelike a manner as possible after death. In postmortem tissue, considerable autolysis may have occurred prior to fixation. Formalin (10%) is the fixative most often used by pathologists.
# '''Dehydration''' - The fixed tissues must be dehydrated in order to embed them in paraffin for sectioning. Water is removed from the tissues by passing them through a series of increasingly concentrated solutions of alcohol.
# '''Clearing''' - Absolute alcohol is not miscible with paraffin. Thus, the alcohol must be removed from the tissue and replaced with an agent that mixes with molten paraffin. The most commonly used clearing agent is xylene. The xylene makes the tissues translucent or “clears” them.
# '''Embedding''' - Following clearing, the tissue is placed in the embedding agent, molten paraffin, and allowed to steep until the tissue is thoroughly infiltrated by the embedding medium. The preparation is then cooled, the paraffin solidifies, and the block of tissue can now be cut with a minimum of distortion. The paraffin infiltrates the interstices of the tissue and thus provides internal support as well as external support for sectioning.
# '''Sectioning''' - The tissue is now cut into very thin slices, usually 5 to 7 microns, with a microtome. The sections are then mounted on glass slides and stained.
# '''Staining''' - For morphologic study, it is necessary to create color contrasts in the tissues by staining. Certain terms are used to distinguish the staining reaction of a cell. The term basophilic indicates that the structure can be stained with the basic dye hematoxylin. All nuclei are basophilic. Cytoplasmic elements may be either basophilic, acidophilic or, neutral. Eosin is the most commonly used acid stain and any acid components that stain positive with eosin are termed eosinophilic.
# '''Other stains''' used in preparing slides – Most slides for histology and pathology are stained with Hematoxylin and Eosin (H&E). Additional staining techniques are utilized to demonstrate specific characteristics of tissues. In any staining process variations in the tissue and the technical procedure may lead to minor color modifications in individual slides, but, in general, the reactions are as stated below.
## '''Masson’s Trichrome stain''' (hematoxylin, acid fuchsin, and aniline blue): nuclei stain black or dark blue; cytoplasm stains red by the acid fuchsin; reticular and collagen fibers stain blue with aniline blue.
## Gomori’s Trichrome stain: Another version of a trichrome stain that stains nuclei - red-purple; normal muscle myofibrils - green-blue with distinct A and I bands; intermyofibrillar muscle membranes – red; and interstitial collagen - green
## '''Periodic acid-Schiff’s reagent (PAS)'''. The PAS method stains glycogen, mucin, connective tissue fibers, and other structures that contain carbohydrates, pink, red, or maroon. The periodic acid converts adjacent 1, 2 glycol groups to aldehydes and the basic Fuchsin of Schiff’s reagent stains the aldehydes. Sometimes Hematoxylin is used as a counter stain giving you a PASH.
## '''Silver stain'''. This special procedure employs silver nitrate to specifically demonstrate reticular fibers, neurofibrils of neurons and granules in enteroendocrine cells. These structures are stained black whereas other tissue components may take on a faint gray background stain without revealing detail.
## '''Toluidine blue'''. Used to demonstrate granules in mast cells. Nuclei are deep blue; mast cell granules are reddish-purple.
## '''Verhoeff-Van Gieson stain (VVG)'''. This method is used for identifying elastic fibers in tissues such as skin, aorta, etc. The elastic fibers will be stained blue-black and background will be stained yellow.

== Using Histologic ==
[[Histologic]] is a constantly-updated, wiki-based comprehensive manual for the teaching of histology. It integrates still images from the [{{SERVER}}/library PEIR Digital Library] and whole slide images from the [http://peir-vm.path.uab.edu PEIR-VM] project. Still images are presented as thumbnails on the right margin of the text; clicking on these thumbnails will expand the images to full resolution. Whole slide images are presented in-line with the text, and can be manipulated using the mouse in much the same fashion as [http://maps.google.com/ Google Maps] or [http://maps.bing.com/ Bing Maps]; use the scroll wheel to change the magnification level, and drag to move the field of view. On the top right corner of the whole slide image viewer, there is a thumbnail of the entire slide that the user may also use for navigational purposes.

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Contributors

2014-07-08T20:40:20Z

Seung Park:

== Acknowledgements ==
This Virtual Microscopy Histology Laboratory Manual is a derivative work from the laboratory teaching materials produced over many years by anatomists from the University of Alabama at Birmingham School of Medicine. The instructors who designed the curriculum, acquired the teaching slide sets and developed this laboratory manual were: George Hand, PhD, Jim Sheetz, PhD and Laura Cotlin, PhD

The virtual microscopy slides described in this manual are primarily scans of original glass slides used in the University of Alabama at Birmingham School of Medicine Cell Biology and Histology teaching program. Additional virtual microscopy slides were kindly contributed by: James L. Fishback, MD, University of Kansas School of Medicine; Mary Ann Sens, MD, PhD, University of North Dakota School of Medicine; and Richard M. Conran, MD, PhD, Uniformed Services University of the Health Sciences.

== Staff ==
=== Faculty Advisors ===
==== Molecular and Cellular Pathology ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=19493 Peter G. Anderson, DVM, PhD]

==== Pathology Informatics ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=61255 Seung Park, MD]

=== Residents, Fellows, and Students ===

==== Summer 2014 ====
* [http://bsc.ua.edu/undergraduate-studies/majors/ Matthew Anderson]
* [http://www.uab.edu/medicine/mstp/current-students Tim Kennell, BS]
* [http://www.uab.edu/medicine/pathology/residency-program/current-residents Alexander Feldman, MD]

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Chapter 3

2014-07-08T20:05:16Z

Seung Park: /* Stratified Epithelium */

== Introduction ==
An epithelium is defined as a tissue that covers or lines the free surfaces of the body. It is one of four fundamental body tissues, with the other three basic tissues being muscle, nervous and connective tissues. Histologically, an epithelium is characterized as being composed of cells sitting upon a basement membrane. The cells are usually arranged in one or more layers with scant intercellular material, or they may sometimes be arranged in cords as in some endocrine glands.

One of the surfaces of an epithelium is exposed either to air or fluid, whereas the other surface is generally attached to a basement membrane that rests upon an underlying connective tissue. With rare exceptions, epithelium is not penetrated by blood vessels and must rely on diffusion processes from the underlying blood supply of the connective tissue for the exchange of nutrients, gases, and wastes (e.g., the endothelial lining of a blood vessel).

Epithelial tissues show numerous specializations of the free surface of cells or of the component cells themselves. For example, the glands of the skin and intestinal tract are derived from epithelium. The embryonic epithelium invaginates into the underlying connective tissue during embryonic development to differentiate into glandular structures. Remember that epithelial tissues are specialized to function in secretion, protection, excretion, absorption, lubrication, sensation, and even reproduction.

One should be able to classify any variety of epithelium according to its structure. An epithelium is usually named according to the appearance of the surface cells. The shape of the cells is important in naming the epithelium. Sometimes the shape referred to is the three dimensional one as in the case of squamous cells (scale-like) and sometimes the two dimensional appearance is referred to as it is seen when the cell is cut vertically to its base. Thus “cuboidal” cells which may appear as squares in sections are actually prismatic in shape with eight sides if seen in their entirety. “Columnar” cells are more elongated prisms. If a cell is surrounded and compressed equally on all sides by other cells, it is usually fourteen sided and appears as a polyhedron in a section.

Identify the following representative varieties of epithelial and be able to interpret the appearance even if it is not cut vertically to the basement membrane.

== Simple Epithelium ==
This type of epithelium has one layer of cells.

=== Simple Squamous Epithelium ===
[[File:HistologicChapter3SimpleSquamousEpithelium.jpg|thumb|200px|Simple squamous epithelium schematic]]
This “pavement epithelium” has flattened scale-like or plate-like cells.

==== Slide 118: Kidney ====
On Slide 118, Kidney (PASH) locate the parietal layer of Bowman’s capsule surrounding the glomeruli (blood capillaries). Identify the layer of simple squamous epithelium which forms the parietal layer of Bowman’s capsule. These cells rest on a pink-staining basement membrane. Note that you can see only the nuclei clearly; the attenuated cytoplasm is indistinct.

<peir-vm>UAB-Histology-00118</peir-vm>

==== Slide 18: Spleen ====
On slide 18, Spleen (H&E), locate the connective tissue capsule that covers the spleen and note the simple squamous epithelium covering the capsule. This lining is called the mesothelium. A mesothelium is defined as a single layer of flattened cells forming an epithelium that lines serous (body) cavities. Note the shapes of the cells. In some regions, they may appear to be slightly cuboidal.

<peir-vm>UAB-Histology-00018</peir-vm>

=== Simple Cuboidal Epithelium ===
[[File:HistologicChapter3SimpleCuboidalEpithelium.jpg|thumb|200px|Simple cuboidal epithelium schematic]]
In this kind of epthelium, the height of each component cell is approximately equivalent to its width.

==== Slide 114: Kidney ====
On slide 114, Kidney (H&E), locate segments of kidney tubules lined with simple cuboidal epithelium. In this type of epithelium the nucleus is round and located in the center of the cell. Other segments of a kidney tubule may be lined by epithelial cells ranging from simple squamous to low columnar or pyramidal (modified columnar) in shape. On slide 118, Kidney (PASH) note how well the PAS stain demonstrates the basement membranes underlying the various epithelial. Cells of different heights are also readily observed on this slide.

<peir-vm>UAB-Histology-00114</peir-vm>

=== Simple Columnar Epithelium ===
[[File:HistologicChapter3SimpleColumnarEpithelium.jpg|thumb|200px|Simple columnar epithelium schematic]]
In this kind of epithelium, the height exceeds the width of the cell.

==== Slide 140: Duodenum ====
On slide 140, duodenum, (PASH), observe the layer of columnar cells that cover the villi. The ovoid nuclei are located in the lower one-half of the cells. Study the shapes of the cells, the location of the nuclei and the specialization of the free surface. These columnar cells are absorptive cells that have microvilli forming a striated border and covered by a PAS-positive glycocalyx. Goblet cells, which are columnar cells modified to secrete mucus, can be seen interspersed among the absorptive columnar epithelial cells. The goblets in these cells exhibit heavy PAS staining.

<peir-vm>UAB-Histology-00140</peir-vm>

=== Pseudostratified Epithelium ===
In this type of simple epithelium the nuclei of the cells appear in irregular layers and may give the false impression that the cells themselves are stratified. In a pseudostratified epithelium all the cells reach the basement membrane even though the nuclei lie at different levels in the tissue. Only the tall cells, however, reach the free surface.

==== Slide 2: Trachea ====
On slide 2, Trachea (H&E), identify the pseudostratified columnar ciliated epithelium which lines the lumen of the trachea. Find an area where the epithelium is intact; it is torn off in places. The epithelium rests on a thick basement membrane. Scattered throughout the epithelium are numerous goblet cells that produce a mucous secretion that traps inspired particles. Study the position of the nuclei. Note once again the cilia of the tall cells of the pseudostratified columnar epithelium.

<peir-vm>UAB-Histology-00002</peir-vm>

==== Slide 6: Epididymis ====
On slide 6, Epididymis (H&E), is a section through the epididymis, a highly coiled genital duct of the male. The cross and oblique sections of this duct are the most numerous of the tubular structures on this slide. Study the pseudostratified columnar epithelium lining the lumen of the epididymis. Goblet cells and cilia are lacking and the basement membrane is not as prominent as it is for the epithelium of the trachea. Tall columnar cells with stereocilia are present. Smaller basal cells can be identified by observing their nuclei that are located close to the basement membrane.

<peir-vm>UAB-Histology-00006</peir-vm>

== Stratified Epithelium ==
[[File:HistologicChapter3StratifiedSquamousEpithelium.jpg|thumb|200px|Stratified squamous epithelium schematic]]
This type of epithelium has more than one layer of cells present. The epithelium is named according to the shape of the surface cells even though the underlying cells may be a different shape. For example, if the surface cells are squamous, but the underlying cells are cuboidal or columnar, the epithelium is a stratified squamous epithelium.

=== Stratified Squamous Epithelium, Noncornified/Nonkeratinized (Moist) ===
On slide 131, Esophagus (H&E) identify the noncornified/nonkeratinized, stratified squamous epithelium. Note the flattened, nucleated surface cells, the “middle zone” of the polyhedral shaped cells, and the basal layer of the polyhedral shaped cells, and the basal layer of columnar cells which rests on the basement membrane. Characteristically, the lower surface of the epithelium is undulated.

==== Slide 131: Esophagus ====
<peir-vm>UAB-Histology-00131</peir-vm>

=== Stratified Squamous Epithelium, Cornified/Keratinized (Dry) ===
On slide 4, Thin skin (H&E) and Slide 46, Thick skin (H&E), study the representative types of cornified/keratinized, stratified squamous epithelium. Note the characteristics of the cells at the various levels. The surface layer of cells, represented by the stratum corneum of the epidermis, lacks nuclei and keratin proteins have replaced the cytoplasm. The surface cells of the skin are constantly desquamated. They are replenished by mitotic divisions occurring in the basal layer of epithelial cells. Note how much thicker the stratum corneum is for thick skin than for thin skin.

==== Slide 4: Thin Skin ====
<peir-vm>UAB-Histology-00004</peir-vm>

==== Slide 46: Thick Skin ====
<peir-vm>UAB-Histology-00046</peir-vm>

=== Stratified Cuboidal and Stratified Columnar Epithelium ===
On slide 111, Epiglottis (H&E), look in the connective tissue underlying the surface epithelium for ducts of glands lined with stratified cuboidal or stratified columnar epithelium. The surface epithelium of the epiglottis is an intermediate type where a change is being made from stratified squamous to pseudostratified columnar epithelium (some of the surface cells are torn off).

==== Slide 111: Epiglottis ====
<peir-vm>UAB-Histology-00111</peir-vm>

=== Transitional Epithelium ===
Transitional epithelium of the urinary passages and bladder shows variations in thickness according to the contracted or dilated state of the structure this epithelium lines. For example, in the contracted urinary bladder, the epithelium may be five or six cell layers thick with the surface cells appearing as large, cuboidal cells that bulge into the lumen. The basal cells are smaller than the surface cells and they interdigitate with the overlying cells. When the bladder fills with urine and becomes distended, the epithelium appears to be only two or three layers thick, and the surface cells are flattened.

On slide 121, Urinary bladder (H&E), identify the transitional epithelium and study its characteristics. Are any of the surface cells binucleated?

==== Slide 121: Urinary Bladder ====
<peir-vm>UAB-Histology-00121</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Main Page

2014-07-08T19:59:01Z

Seung Park: /* Teaching */

<div id="mf-home">
Welcome to the Pathology Education Instructional Resource (PEIR), a web teaching resource and informatics training grounds directed by [https://services.medicine.uab.edu/facultyDirectory/FacultyData.asp?s_lname=Park&s_keyword=&s_fname=Seung&FacultyTypeID=&s_Department_Name=&s_ResearchTitle=&FID=61255 Seung Park, MD] and [https://services.medicine.uab.edu/facultyDirectory/FacultyData.asp?Entity=JHS&vwAllfacultyPage=1&FID=19493 Peter Anderson, DVM, PhD]. Please contact one of us directly if you have any interest in contributing and/or editing content.

== PEIR Projects ==
=== Image Libraries ===
* The [{{SERVER}}/library PEIR Digital Library] contains more than 30,000 curated teaching images, and is our flagship project.
* [http://peir-vm.path.uab.edu/ PEIR-VM] is a compehensive teaching repository of whole slide images.

=== Teaching ===
* [[IPLab]] is a comprehensive online course in classic pathology.
* [[Histologic]] is a comprehensive histology manual.
* [[Cytologically Yours]] is an online cytopathology teaching resource for pathology residents and fellows.
* [[This Is Your Brain On Informatics]] consists of the class notes for GBS788/STP2146: "this is your brain, THIS IS YOUR BRAIN ON INFORMATICS".

__NOGLOSSARY__

Histologic:Contributors

2014-07-08T19:57:47Z

Seung Park: /* Faculty Advisors */

== Acknowledgements ==
This Virtual Microscopy Histology Laboratory Manual is a derivative work from the laboratory teaching materials produced over many years by anatomists from the University of Alabama at Birmingham School of Medicine. The instructors who designed the curriculum, acquired the teaching slide sets and developed this laboratory manual were: George Hand, PhD., Jim Sheetz, PhD. and Laura Cotlin, PhD.

The virtual microscopy slides described in this manual are primarily scans of original glass slides used in the University of Alabama at Birmingham School of Medicine Cell Biology and Histology teaching program. Additional virtual microscopy slides were kindly contributed by: James L. Fishback, MD, University of Kansas School of Medicine; Mary Ann Sens, MD, PhD, University of North Dakota School of Medicine; and Richard M. Conran, MD, PhD., Uniformed Services University of the Health Sciences.

== Staff ==
=== Faculty Advisors ===
==== Molecular and Cellular Pathology ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=19493 Peter G. Anderson, DVM, PhD]

==== Pathology Informatics ====
* [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=61255 Seung Park, MD]

=== Residents, Fellows, and Students ===

==== Summer 2014 ====
* [http://bsc.ua.edu/undergraduate-studies/majors/ Matthew Anderson]
* [http://www.uab.edu/medicine/mstp/current-students Tim Kennell, BS]
* [http://www.uab.edu/medicine/pathology/residency-program/current-residents Alexander Feldman, MD]

{{Template:Histologic}}

[[Category:Histologic]]

Histologic

2014-07-08T19:54:10Z

Seung Park:

== [[Histologic:Chapter 1|Chapter 1: Histology ]] ==
* [[Histologic:Chapter 1#Introduction|Introduction]]
* [[Histologic:Chapter 1#Overview_of_Tissue_Preparation_and_Staining_for_Microscopy|Overview of Tissue Preparation and Staining for Microscopy]]

== [[Histologic:Chapter 2|Chapter 2: The Cell]] ==
* [[Histologic:Chapter 2#Cells,_Organelles,_and_Inclusions|Cells, Organelles, and Inclusions]]
* [[Histologic:Chapter 2#Mitosis|Mitosis]]

== [[Histologic:Chapter 3|Chapter 3: Epithelial Cells]] ==
* [[Histologic:Chapter 3#Introduction|Introduction]]
* [[Histologic:Chapter 3#Simple_Epithelium|Simple Epithelium]]
* [[Histologic:Chapter 3#Stratified_Epithelium|Stratified Epithelium]]

== [[Histologic:Chapter 4|Chapter 4: Support Cells and the Extracellular Matrix]] ==
* [[Histologic:Chapter 4#Introduction|Introduction]]

== [[Histologic:Chapter 5|Chapter 5: Contractile Cells]] ==
* [[Histologic:Chapter 5#Introduction|Introduction]]

== [[Histologic:Chapter 6|Chapter 6: Nervous Tissue]] ==
* [[Histologic:Chapter 6#Introduction|Introduction]]

== [[Histologic:Chapter 7|Chapter 7: Blood Cells]] ==
* [[Histologic:Chapter 7#Introduction|Introduction]]

== [[Histologic:Chapter 8|Chapter 8: Immune System]] ==
* [[Histologic:Chapter 8#Introduction|Introduction]]

== [[Histologic:Chapter 9|Chapter 9: Blood and Lymphatic Circulatory Systems and Heart]] ==
* [[Histologic:Chapter 9#Introduction|Introduction]]

== [[Histologic:Chapter 10|Chapter 10: Respiratory System]] ==
* [[Histologic:Chapter 10#Introduction|Introduction]]

== [[Histologic:Chapter 11|Chapter 11: Alimentary Tract]] ==
* [[Histologic:Chapter 11#Introduction|Introduction]]

== [[Histologic:Chapter 12|Chapter 12: Liver]] ==
* [[Histologic:Chapter 12#Introduction|Introduction]]

== [[Histologic:Chapter 13|Chapter 13: Musculoskeletal System]] ==
* [[Histologic:Chapter 13#Introduction|Introduction]]

== [[Histologic:Chapter 14|Chapter 14: Endocrine System]] ==
* [[Histologic:Chapter 14#Introduction|Introduction]]

== [[Histologic:Chapter 15|Chapter 15: Urinary System]] ==
* [[Histologic:Chapter 15#Introduction|Introduction]]

== [[Histologic:Chapter 16|Chapter 16: Male Reproductive System]] ==
* [[Histologic:Chapter 16#Introduction|Introduction]]

== [[Histologic:Chapter 17|Chapter 17: Female Reproductive System]] ==
* [[Histologic:Chapter 17#Introduction|Introduction]]

== [[Histologic:Chapter 18|Chapter 18: Skin and Breast]] ==
* [[Histologic:Chapter 18#Introduction|Introduction]]

== [[Histologic:Chapter 19|Chapter 19: Special Senses]] ==
* [[Histologic:Chapter 19#Introduction|Introduction]]

== [[Histologic:Acknowledgements and Staff|Acknowledgements and Staff]] ==
* [[Histologic:Acknowledgements and Staff#Acknowledgements|Acknowledgements]]
* [[Histologic:Acknowledgements and Staff#Staff|Staff]]

[[Category:Histologic]]

Histologic:Chapter 2

2014-07-08T19:42:45Z

Seung Park: /* Mitosis */

== Cells, Organelles, and Inclusions ==
[[File:HistologicChapter2Cell.jpg|thumb|200px|Cell schematic]]
To begin the study of cellular structure, you are asked to identify several kinds of cells, cellular specializations and inclusions of cells. Learn to distinguish between the nucleolus, the nucleus, and the cytoplasm of a cell. Observe the appearance of the chromatin, the position of the nucleus within the cell and the staining characteristics of the cytoplasm. Note the size of the cells, the density of similar cells, and their arrangement in the tissue. As you study the different cell types, keep in mind that sectioned material is being observed and that the appearance of the cell may vary depending on the plane of section.

A cell usually contains only one nucleus, but some cells may be binucleate. The nucleus often conforms to the shape of the cell being spherical, ovoid, or elongated. Other nuclei may be crescent shaped or lobated. It can be flattened towards the base of the cell when the pressure from cytoplasmic constituents “pushes it” there. Nucleoli may or may not be present. In sectioned material, the nucleus or nucleolus may appear to be absent from a cell because they were not in the plane of sectioning. If the cell is in a phase of mitosis, the nucleus will appear different from nuclei of other non-mitotic cells of the tissue.

The cytoplasm often exhibits modifications according to the specific functions of the cell or the tissue. Muscle cells have contractile myofibrils. Secretory cells of the salivary glands possess numerous secretory granules. Epithelial cells of the skin produce a protein called keratin for protection. The epithelial lining of the respiratory tract may possess cilia. White blood cells may contain primary and specific granules. Neurons possess neurofibrils, etc. The list is almost endless.

NOTE: The objective of this first exercise is merely to gain an awareness of the varieties of cell sizes, cell shapes, cell types, cell staining characteristics and cell organelles or inclusions. You are not expected, at this time, to become familiar with the over-all structure of the tissues and organs where these cells are located.

=== Microscopic Study: Architecture ===
==== Slide 25: Spinal Cord ====
On slide 25, Spinal Cord (Thionin) find under low power the cell bodies of multipolar neurons located in the two anterior horns of the gray matter (if the slide is held towards the light, the gray matter appears H-shaped). With medium power, identify a cell body containing a large pale nucleus and a darkly stained nucleolus. Study this cell under high power. The irregular, granular-like, basophilic staining masses within the cytoplasm are called Nissl bodies. They consist of free ribosomes and granular endoplasmic reticulum.

<peir-vm>UAB-Histology-00025</peir-vm>

==== Slide 73: Spinal Ganglion ====
On slide 73, Spinal Ganglion (silver) identify the large cell bodies of the ganglion cells associated with the sensory root of spinal nerves. The cell bodies of these unipolar neurons range in size from 15μm to 100μm. Compare a number of ganglion cell bodies for size differences. The centrally located nuclei stain palely and appear as clear spaces in the middle of the granular cytoplasm. With careful observation you will see nuclei of much smaller cells immediately surrounding the cell bodies of the ganglion cells. These represent satellite cells. Note how much smaller they are than the nuclei of the ganglion cells.

<peir-vm>UAB-Histology-00073</peir-vm>

==== Slide 149: Liver ====
On slide 149, Liver (H&E) observe that the hepatocytes (liver parenchymal cells) appear to be arranged as rows or cords of cells. Actually the tridimensional arrangement of these cells is in cellular sheets or plates which are separated by blood-filled spaces called sinusoids. Red blood corpuscles may be seen in some of the sinusoids. Note that cell boundaries can be distinctly seen between many of the liver cells. The polyhedral- shaped hepatocytes have round, centrally located nuclei containing one or more nucleoli and scattered clumps of chromatin. Binucleated hepatocytes can be found. Note the granularity of the eosinophilic staining cytoplasm

<peir-vm>UAB-Histology-00149</peir-vm>

==== Slide 154: Pancreas ====
Slide 154, Pancreas (H&E) has cells which distinctly exhibit a difference between basophilic regions and acidophilic regions. After studying the cells with medium power, turn to high power to complete your study. Observe that the cell boundaries are indistinct. Note that the cytoplasm in the basal region of the acinar cells is basophilic. Here the ribonucleoproteins associated with rough endoplasmic reticulum and the large numbers of mitochondria are sufficiently dense to stain with the basic dye. Note, however, the red staining of the apical half of the acinar cells. This acidophilic staining cytoplasm contains numerous secretory granules that stain brightly with the eosin stain. The nuclei are basophilic staining as are the nuclei of all cells. Observe that the nuclei are characteristically located in the basal one-third of the cell. Nucleoli may be seen in many cells.

<peir-vm>UAB-Histology-00154</peir-vm>

=== Microscopic Study: Cell Types ===
==== Slide 2: Trachea ====
[[File:HistologicChapter2Cilia.jpg|thumb|200px|Cilia schematic]]
On slide 2, Trachea (H &E) identify the cilia on the tall cells of the pseudostratified columnar epithelium that line the lumen of the trachea. Each cilium is derived from a basal body, represented here in aggregate by the dark lines where the cilia attach to the cell. In some regions of this tissue the cilia are absent or the entire epithelium is missing. This is artifact.

<peir-vm>UAB-Histology-00002</peir-vm>

==== Slide 89: Skeletal Muscle ====
On slide 89, Skeletal Muscle (H&E) identify muscle fibers cut in longitudinal section. Under high power note the striated appearance of the muscle cells. Although not readily visible, the cytoplasm of these cells contains myofibrils, the contractile elements of the cell. The arrangement of these myofibrils and their subunits, the myofilaments, impart the striated appearance to the muscle fibers.

<peir-vm>UAB-Histology-00089</peir-vm>

==== Slide 31: Ileum ====
On slide 31, Ileum (H &E) identify with low power the villi projecting from one side of the tissue. With high power identify the tall cells (simple columnar cells) which cover these villi. On the free surface of these cells can be seen a dense line representing the striated border. This border consists of cytoplasmic processes termed microvilli that greatly increase the absorptive area of the small intestine. In light microscopy, the microvilli appear vertically striated so these projections form a “striated border.”

<peir-vm>UAB-Histology-00031</peir-vm>

== Mitosis ==
[[File:HistologicChapter2Mitosis.jpg|thumb|200px|Overview of mitosis]]
Mitosis can be viewed as the means whereby identical genetic material, contained in the chromosomes, is distributed to two daughter nuclei. It can be divided into four stages, each characterized by certain features of nuclear or chromosome morphology and chromosome movement. The stages are arbitrary in that mitosis is a continuous process from its inception at prophase through the stages of metaphase and anaphase to the final stage of telophase. The nucleus of a cell that is not dividing is in the interphase stage.

The number of mitotic figures in a tissue is an index of the rate of turnover of the component cells. In benign tumors, mitotic figures are few in numbers, whereas in malignant tumors, mitotic figures are more numerous and may include many bizarre forms. Hence, the recognition of mitotic figures is one criterion for the interpretation of various kinds of pathology of a tissue.

=== Microscopic Study: Mitosis ===
On slide 34, Mitosis (Iron H), are longitudinal sections of onion root tips in which cells have been fixed in various stages of mitosis. Learn to identify the characteristic arrangement of the chromatin in each state.

==== Slide 34: Mitosis ====
<peir-vm>UAB-Histology-00034</peir-vm>

{{Template:Histologic}}

[[Category:Histologic]]

Histologic:Contributors

2014-07-08T19:39:32Z

Seung Park: /* Residents, Fellows, and Students */

== Acknowledgements ==
This Virtual Microscopy Histology Laboratory Manual is a derivative work from the laboratory teaching materials produced over many years by anatomists from the University of Alabama at Birmingham School of Medicine. The instructors who designed the curriculum, acquired the teaching slide sets and developed this laboratory manual were: George Hand, PhD., Jim Sheetz, PhD. and Laura Cotlin, PhD.

The virtual microscopy slides described in this manual are primarily scans of original glass slides used in the University of Alabama at Birmingham School of Medicine Cell Biology and Histology teaching program. Additional virtual microscopy slides were kindly contributed by: James L. Fishback, MD, University of Kansas School of Medicine; Mary Ann Sens, MD, PhD, University of North Dakota School of Medicine; and Richard M. Conran, MD, PhD., Uniformed Services University of the Health Sciences.

== Staff ==
=== Faculty Advisors ===
* ''Molecular and Cellular Pathology'': [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=19493 Peter G. Anderson, DVM, PhD]
* ''Pathology Informatics'': [http://services.medicine.uab.edu/facultydirectory/FacultyData.asp?FID=61255 Seung Park, MD]

=== Residents, Fellows, and Students ===

==== Summer 2014 ====
* [http://bsc.ua.edu/undergraduate-studies/majors/ Matthew Anderson]
* [http://www.uab.edu/medicine/mstp/current-students Tim Kennell, BS]
* [http://www.uab.edu/medicine/pathology/residency-program/current-residents Alexander Feldman, MD]

{{Template:Histologic}}

[[Category:Histologic]]