Figure 1.

The structure on an artery wall. Three layers form the standard artery wall: the tunica intima, the tunica media, and the tunica adventitia (externa). The intimia (the most inner one) consists of the endothelium (a single layer of cells), connective tissue, and a basal layer of elastic tissue called the internal elastic lamina. Concentric layers of vascular smooth muscle cells and elastin-rich extracellular matrix make the tunica media, which is separated from adventitia by the external elastic lamina. The tunica adventitia is the outer layer and is formed by fibroblasts, collagen, mast cells, nerve endings, and vasa vasorum [35].