Two subsequent different types of bone formation, we respectively named static osteogenesis (SO) and dynamic osteogenesis (DO), were observed in intramembranous ossification centers of newborn rabbits and chick embryos as well as during bone repair. In all cases the onset of intramembranous ossification is characterized by the appearance, around the vessels, of pluristratified cords of unexpect...

Hedgehog (Hh) signaling has been implicated in the development of osteoblasts and osteoclasts whose balanced activities are critical for proper bone formation. Since many mouse mutants in the Hh pathway are embryonic lethal, questions on the exact effects of Hh signaling on osteogenesis remain. Using zebrafish larvae mutant in Indian Hedgehog, patched1, patched2 and suppressor of fused (dre), w...

BACKGROUND Ischemia-reperfusion of bone occurs in a variety of clinical conditions, such as orthopedic arthroplasty, plastic gnathoplasty, spinal surgery, and amputation. Usually, cellular models of hypoxia-reoxygenation reflect in vivo models of ischemia-reperfusion. With respect to hypoxia-reoxygenation conditions, the effects of remifentanil on osteogenesis have received little attention. Th...

Endothelial progenitor cells (EPCs) contribute to neovascularization and vascular repair, and may exert a beneficial effect on the clinical outcome of sepsis. Osteoblasts act as a component of "niche" in bone marrow, which provides a nest for stem/progenitor cells and are involved in the formation and maintenance of stem/progenitor cells. Fibroblast growth factor receptor 1 (FGFR1) can regulate...

Soybean is a major dietary source of isoflavones, particularly daidzein and genistein, which stimulate osteoblastic functions that are initiated by binding to estrogen receptor (ER)-α and ER-β found on osteoblasts. However, coupled with a low expression of ER-α and ER-β in osteoclasts, the inhibitory effects of soy isoflavones on osteoclast differentiation is likely mediated through paracrine f...

Transcription factors play a key role in determination of the fate of the cells in osteoblastic and chondrocytic lineage. A runt family member, Cbfa, is indispensable for osteoblastic differentiation. Sox 9 and scleraxis are involved in the phenotypic expression in chondrocytes and the cells of early stage connective tissues. These transcription factors will give us a clue to unravel interactio...

The skeleton is maintained throughout life via the finely tuned actions of osteoblasts and osteoclasts, with disruption in this balance eventually leading to bone disease. The exact mechanisms balancing these actions are not fully known, although several regulatory systems are known to be involved. The involvement of purinergic signalling in bone has come to light over the past 20 years or so. ...

Bone remodelling is carried out by 'bone multicellular units' ([Formula: see text]s) in which active osteoclasts and active osteoblasts are spatially and temporally coupled. The refilling of new bone by osteoblasts towards the back of the [Formula: see text] occurs at a rate that depends both on the number of osteoblasts and on their secretory activity. In cortical bone, a linear phenomenologic...

The differentiation of osteoblasts from mesenchymal precursors requires a series of cell fate decisions controlled by a hierarchy of transcription factors. Among these are RUNX2, Osterix (OSX), ATF4, and a large number of nuclear coregulators. During bone development, initial RUNX2 expression coincides with the formation of mesenchymal condensations well before the branching of chondrogenic and...

The activities of osteoclasts, which degrade bone, and osteoblasts, which form bone, are coordinated to maintain bone homeostasis. Zhao et al. (2006) now demonstrate bidirectional signaling between these two cell populations via the transmembrane ligand ephrinB2 expressed by osteoclasts and its receptor EphB4 expressed by osteoblasts. Such bidirectional signaling limits osteoclast activity whil...