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Vascular Development - Anatomy & Physiology (view source)
Revision as of 15:17, 10 July 2008
, 15:17, 10 July 2008no edit summary
===Angiogenesis===
===Angiogenesis===
The sprouting of new capillaries from existing blood vessels occurs when surrounding cells become hypoxic. A low partial pressure of oxygen causes an increase in levels of hypoxia-inducible factor (HIF), this in turn stimulates cells to release vascular endothelial growth factor (VEGF) leading to new vessel formation. Other growth factors such as angiopoietin also play an important role. Angiopoietin-1 interacts with the Tie-2 receptor on endothelial cells at the sites where sprouting occurs. Platelet derived growth factor (PDGF) and transforming growth factor-β (TGF-β) influence the maturation of the capillary network. Angiopoietin-2 expression in the absence of VEGF leads to vessel regression and apoptosis.