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== Bone ==

Bone is a hard connective tissue in which the fibers are impregnated with mineral substance, chiefly calcium phosphate and calcium carbonate. Bone is classified according to its morphological appearance as either compact or spongy (cancellous) bone. The only difference in the two kinds of bone is in the size and number of spaces present. Compact bone is more solid than spongy bone, the latter being a latticework of slender, irregular trabeculae. Bone is also classified according to its origin. Membrane bone (intramembranous bone) develops within a connective tissue membrane (“a mature mesenchyme”) whereas endochondral bone (intracartilaginous bone) develops by replacing a cartilage template that is formed before bone replaces it.