Angiogenesis

Article By:

Weinstein, Brant M. National Institute of Child Health and Human Services, Bethesda, Maryland.

Last reviewed:August 2019

DOI:https://doi.org/10.1036/1097-8542.801180

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• Angiogenesis, published June 2014:Download PDF Get Adobe Acrobat Reader

The origin and development of blood vessels. Angiogenesis is the process through which new blood vessels are formed. Blood vessels (Fig. 1) are composed of two basic cell types: vascular endothelial cells and periendothelial cells (including vascular smooth muscle cells and elongated contractile cells called pericytes, both of which support the underlying endothelial cells). The inner epithelial lining of all blood vessels, adjacent to the lumen, is a single layer of endothelial cells. In larger blood vessels, such as arteries and veins, the inner endothelial lining, called the tunica intima (Fig. 2), is surrounded by a medial layer, the tunica media, composed of multiple layers of vascular smooth muscle cells embedded in an elastin-rich extracellular matrix. The tunica media layer is surrounded by an extracellular matrix–rich layer called the tunica adventitia (also referred to as the tunica externa) [Fig. 2]. In contrast, capillary walls consist of only a single layer of endothelial cells, sometimes surrounded by pericytes. See also: Blood; Blood vessel; Elastin; Vascular development

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