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Histology of compact bone showing osteon. Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the Haversian canal. The Haversian canal contains the bone's blood supplies. The boundary of an osteon is the cement line.
The channels are formed by concentric layers called lamellae, which are approximately 50 μm in diameter. The Haversian canals surround blood vessels and nerve cells throughout bones and communicate with osteocytes (contained in spaces within the dense bone matrix called lacunae) through connections called canaliculi.
Flat bones are thin and generally curved, with two parallel layers of compact bone sandwiching a layer of spongy bone. Most of the bones of the skull are flat bones, as is the sternum. [39] Sesamoid bones are bones embedded in tendons. Since they act to hold the tendon further away from the joint, the angle of the tendon is increased and thus ...
In an ordinary microscopic section, viewed by transmitted light, they appear as fusiform opaque spots. Each lacuna is occupied during life by a branched cell, termed an osteocyte, bone-cell or bone-corpuscle. Lacunae are connected to one another by small canals called canaliculi. A lacuna never contains more than one osteocyte.
In a long bone it is a thin disc of hyaline cartilage that is positioned transversely between the epiphysis and metaphysis. In the long bones of humans, the epiphyseal plate disappears by twenty years of age. physis, "the growth part" metaphysis: The region of a long bone lying between the epiphysis and diaphysis.
Osteons are components or principal structures of compact bone. During the formation of bone spicules, cytoplasmic processes from osteoblasts interconnect. This becomes the canaliculi of osteons. Since bone spicules tend to form around blood vessels, the perivascular space is greatly reduced as the bone continues to grow. When replacement to ...
Diameter of canaliculi in human bone is approximately 200 to 900 nm. [1] In bovine tibia diameter of canaliculi was found to vary from 155 to 844 nm (average 426 nm). [ 2 ] In mice humeri it varies from 80 to 710 nm (average 259 nm), while diameter of osteocytic processes varies from 50 to 410 nm (average 104 nm).
They are the most common cell type in bone (31,900 per cubic millimeter in bovine bone to 93,200 per cubic millimeter in rat bone). [6] Most of the receptor activities that play an important role in bone function are present in the mature osteocyte. [6] Osteocytes are an important regulator of bone mass.