- Discussion:
- see:
osteocytes and
osteoclasts
- arise from marrow stroma cells, and are found on the surfaces where bone is being formed;
- may require
bone morphogenic proteins for induction into osteoblasts;
- generally regarded as bone forming cells;
- most obvious function is to synthesize osteoid;
- in certain situations, they initiate bone resorption;
- osteoblasts synthesize
collagen and to control its subsequent
mineralization;
- w/ rapid osteogenesis, cells are usually quite plump & cuboidal.
- when mature bone is being formed slowly, lining osteoblasts tend to be thin, flat, and elongated;
- osteoblasts have cytoplasmic processes that extend to adjacent osteoblasts & into bone substance by way of canaliculi to join processes of
osteocytes;
- both cytoplasm & nucleus of osteoblasts contain enzyme
alkaline phosphatase, which can be used as a marker for osteoblast activity;
- bone formation is a two-step process that involves matrix formation &
mineralization;
-
receptors:
- estrogen
-
parathyroid hormone
-
vit D
- Histology:
- they vary in size and shape, most being 20-30 micrometers in diameter;
- they are usually closely arranged in a dense single layer of cells covering bone surface, but where bone formation is active, there may be several layers of cells;
The effect of glucocorticoids on osteoblast function. The effect of corticosterone on osteoblast expression of beta 1 integrins.
