Osteocyte

An osteocyte is a bone cell.

They are up to 30 micrometers long and 15 micrometers wide. The osteocyte is a flattened star shaped cell with a central nucleus surrounded by acidophilic cytoplasm.

The osteocytes live for approximately ten years and are completely surrounded by the bone matrix. They are found within the bone in a hugely inter-connected cavity system (lacunae and canaliculi), and are connected to each other. These cell bodies are contained in the lacunae whereas the extensions to neighbouring cells are found in the canaliculi, which run through the matrix. There is a narrow area that only contains collagen fibrils and interstitial fluid around each cell and its extensions. This cavity system provides the food supply and communication for osteocytes.

The osteocyte is obtained from maturation of the osteoblast, a cell which actively synthesises the bone matrix. The osteocytes are effectively encased in the bone tissue but continue to synthesise bone at a slower rate.

They have mecanoreceptors which provide them with information about the pressure on the bones and enables their synthetic activity to be regulated.

They synthesise collagen fibres and regulate osteoclast activity and mineralisation.