During bone formation, an osteoblast is left behind and buried in the bone matrix as an "osteoid osteocyte", which maintains contact with other osteoblasts through extended cellular processes [REF].
Palumbo et al.(1990) distinguish three cell types from osteoblast to mature osteocyte: type I preosteocyte (osteoblastic osteocyte), type II preosteocyte (osteoid osteocyte), and type III preosteocyte (partially surrounded by mineral matrix) [REF].