What are osteocytes in biology?

Osteocytes are the most abundant type of bone cells. They lie within the substance of fully formed bone, occupying a small chamber known as a lacuna, which is contained in the calcified matrix of bone. Each lacuna houses one osteocyte. 

The cells are flat and almond shaped with a length of about15 micrometers and a depth of about 7 micrometers. A mature osteocyte has a single membraned-nucleus with one or two nuclei, rough endoplasmic reticulum, and reduced Golgi complex. 

Osteocytes are derived from osteoblasts, which are bone-forming cells. They are long lived bone cells. Their viability is maintained by means of small channels known as canaliculi, which facilitate the exchange of nutrients and waste products.