Bones

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heets of calcified matrix, know as lamellae. Individual lamellae range between 4um and 12um in thickness. Small channels radiate through the matrix, interconnecting lacunae and linking them to nearby blood vessels. These canaliculi contain cytoplasmic extensions of the osteocytes and their extensions provide a route for the diffusion of nutrients and waste products.
Microscopic organization of bone tissue can be divided into two bone types. Primary or woven bone is bone which is produced de novo by intramembranous or endochondral ossification. It has a highly irregular arrangement. Woven bone is weaker than lamellar bone due to the random organization of collagen fibers and greater number of osteocytes. Secondary or lamellar bone is highly organized mature bone. The collagen framework and mineralized matrix are arranged in lamellae or layers; collagen fibers of each lamella run in opposite helical directions to those in adjacent lamellae, thereby increasing the strength of the microscopic unit.
Lamellar bone exists in three forms: osteona...