ABSTRACT
Exceptions to this stable condition occur during the cyclical growth of vessels in the ovarian corpus luteum or during pregnancy. Pathological conditions during which angiogenesis occurs are tissue repair during
wound healing and during the growth of a tumor. Initiation of angiogenesis requires a shi in the balance between activators and suppressors. Important activators of angiogenisis include vascular endothelial growth factor-A (VEGF-A), matrix metalloproteinases (MMPs), placenta growth factor (PlGF), broblast growth factor (FGF), and hepatocyte growth factor (HGF). Endogenous inhibitors of angiogenesis include thrombospondins (THSBs), endostatin, angiostatin, and cytokines such as interleukin-12.
