by Robert C. Mellors, M.D., Ph.D.
I. NORMAL BONE
The cellular activities of osteoblasts, osteocytes, and osteoclasts are
essential to the process. Osteoblasts synthesize the collagenous precursors
of bone matrix and also regulate its mineralization. As the process of
bone formation progresses, the osteoblasts come to lie in tiny spaces (lacunae)
within the surrounding mineralized matrix and are then called osteocytes.
The cell processes of osteocytes occupy minute canals (canaliculi) which
permit the circulation of tissue fluids. To meet the requirements of skeletal
growth and mechanical function, bone undergoes dynamic remodeling by a
coupled process of bone resorption by osteoclasts and reformation by osteoblasts.
Osteoblasts and Bone Matrix
production of the extracellular organic matrix (osteoid);
mineralization of the matrix to form bone;
and bone remodeling by resorption and reformation.
Osteoclasts and Bone Resorption