Source:http://linkedlifedata.com/resource/umls/id/C0225342
MSH: The outermost covering of organs, blood vessels, and other such structures in the body.,NCI: The outer connective tissue layer of the blood vessel wall. The adventitia consists of longitudinally arranged collagen fibers, elastic fibers, smooth muscle, fibroblasts, nerves and the vasa vasorum. It is thicker in veins than in arteries.