Angiogenesis blood tissue process 1 Illustration and Icon

A schematic depicts angiogenic sprouting from a pre‑existing microvessel into surrounding connective tissue. Endothelial cells (ECs) form the vessel wall and extend a tip cell into the extracellular matrix (ECM), guided by gradients of pro‑angiogenic factors such as VEGF (vascular endothelial growth factor). Circulating blood cells occupy the vessel lumen. In hierarchical terms, endothelial cells are specialized cells within capillary tissue of the cardiovascular system. In vascular biology and physiology, this process enables neovascularization to supply oxygen and nutrients during wound healing and, in pathology, supports tumor growth. The site shown is interstitial tissue adjacent to a small blood vessel.