The adventitia, endothelium and atherosclerosis.

Despite many theories, the initiating circumstances for the development of atherosclerosis remain obscure. The development of animal models of atherosclerosis was based upon the different theories of the origins of atherosclerosis which suggested that it originates at the intimal surface of the vessel. A more recent model of atherosclerosis involves perivascular manipulation of the vessel by positioning of a hollow silastic collar around the artery. In this model, several of the features seen in early human atherosclerosis are generated within a period of 7 days. It is hypothesized that arterial wall hypoxia following occlusion of the vasa vasorum may be the initial lesion of atherosclerosis, and hence that in some cases atherosclerosis is a disease of the outer layers of the arterial wall.