<P> An osteocyte, a star - shaped type of bone cell, is the most commonly found cell in mature bone tissue, and can live as long as the organism itself . The adult human body has about 42 billion osteocytes . Osteocytes have an average half life of 25 years, they do not divide, and they are derived from osteoprogenitors, some of which differentiate into active osteoblasts . Osteoblasts / osteocytes develop in mesenchyme . </P> <P> In mature bone, osteocytes and their processes reside inside spaces called lacunae (Latin for a pit) and canaliculi, respectively . When osteoblasts become trapped in the matrix that they secrete, they become osteocytes . Osteocytes are networked to each other via long cytoplasmic extensions that occupy tiny canals called canaliculi, which are used for exchange of nutrients and waste through gap junctions . </P> <P> Although osteocytes have reduced synthetic activity and (like osteoblasts) are not capable of mitotic division, they are actively involved in the routine turnover of bony matrix, through various mechanosensory mechanisms . They destroy bone through a rapid, transient (relative to osteoclasts) mechanism called osteocytic osteolysis . Hydroxyapatite, calcium carbonate and calcium phosphate is deposited around the cell . </P> <P> Osteocytes have a stellate shape, approximately 7 micrometers deep and wide by 15 micrometers in length . The cell body varies in size from 5 - 20 micrometers in diameter and contain 40 - 60 cell processes per cell, with a cell to cell distance between 20 - 30 micrometers . A mature osteocyte contains a single nucleus that is located toward the vascular side and has one or two nucleoli and a membrane . The cell also exhibits a reduced size endoplasmic reticulum, Golgi apparatus and mitochondria, and cell processes that radiate towards the mineralizing matrix . Osteocytes form an extensive connecting syncitial network via small cytoplasmic / dendritic processes in canaliculi . </P>

Calcium carbonate and calcium phosphate are deposited around the cell