OSTEOCYTE

a cell that lies within the substance of fully formed bone. It occupies a small chamber called a lacuna, contained in the calcified matrix of bone. Osteocytes derive from osteoblasts, or bone-forming cells, and are essentially osteoblasts surrounded by the products they secreted. Cytoplasmic processes of the osteocyte extend away from the cell toward other osteocytes in small channels called canaliculi. By means of these canaliculi, nutrients and waste products are exchanged to maintain the viability of the osteocyte. The osteocyte is not actively engaged in synthesizing bone as is the osteoblast, but it is unclear what function it does perform. It has been suggested that the osteocyte may aid in calcium removal from bone when the body calcium level drops too low.