| advertise add site services publishers database health videos | ![]() | about toolbar stats live show health store more stuff JOIN/LOGIN |
Osteoporosis Australia - Osteoblast Magazine osteoporosis.org.au | Announces Successful Derivation Of Osteoblasts From Human Embryonic... geron.com | Multiple myeloma treatment by osteoblast suppression described : Rocky... rockymountainbmt.com |
An osteoblast (from the Greek words for "bone" and "germ" or embryonic) is a mononucleate cell that is responsible for bone formation. Osteoblasts produce osteoid, which is composed mainly of Type I collagen. Osteoblasts are also responsible for mineralization of the osteoid matrix. Bone is a dynamic tissue that is constantly being reshaped by osteoblasts, which build bone, and osteoclasts, which resorb bone. Osteoblast cells tend to decrease as individuals become elderly, thus decreasing the natural renovation of the bone tissue.[1]
[edit] OsteogenesisOsteoblasts arise from osteoprogenitor cells located in the periosteum and the bone marrow. Osteoprogenitors are immature progenitor cells that express the master regulatory transcription factor Cbfa1/Runx2. Osteoprogenitors are induced to differentiate under the influence of growth factors, in particular the bone morphogenetic proteins (BMPs). Aside from BMPs, other growth factors including fibroblast growth factor (FGF), platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF-β) may promote the division of osteoprogenitors and potentially increase osteogenesis. Once osteoprogenitors start to differentiate into osteoblasts, they begin to express a range of genetic markers including Osterix, Col1, BSP, M-CSF, ALP, osteocalcin, osteopontin, and osteonectin. Although the term osteoblast implies an immature cell type, osteoblasts are in fact the mature bone cells entirely responsible for generating bone tissue in animals and humans. [edit] Morphology and histological stainingHematoxylin and eosin staining reveals that the cytoplasm of osteoblasts is basophilic due to the presence of a large amount of rough endoplasmic reticulum. A large Golgi apparatus is also present in the centre. The nucleus is spherical and large. Active osteoblasts synthesize, and stain positively for, Type-I collagen and alkaline phosphatase. [edit] Osteoblasts and osteocytesMain article: osteocyte Osteoblasts that become trapped in the bone matrix become osteocytes. They cease to generate osteoid and mineralized matrix, and instead act in a paracrine manner on active osteoblasts. They are believed to act in a mechanosensory manner. [2] [3] [edit] References
[edit] See also[edit] External links
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ↑ top of page ↑ | about thumbshots |