Vascular Endothelial Growth Factor （VEGF） is a sub-family of growth factors produced by cells, which stimulates vasculogenesis and angiogenesis. VEGF's normal function is to create new blood vessels during embryonic development, new blood vessels after injury, muscle following exercise, and new vessels （collateral circulation） to bypass blocked vessels. Mouse and rat express alternately spliced isoforms of 120, 164, and 188 amino acids （a.a.） in length.Rat VEGF164 shares 97%a.a. sequence identity with corresponding regions of mouse, 88% with human and bovine, 89% with porcine and canine, and 90% with feline and equine VEGF, respectively.During pathological neovascularization, both the absolute and relative expression levels for VEGF164 increased to a greater degree than during physiological neovascularization.