The development of vasa vasorum of the human aorta in various conditions. A morphometric study.

The developmental behavior of vasa vasorum under various conditions was studied on the wall tissues of aorta and great arteries from 29 autopsy cases, where the length density (LA) of vasa vasorum in a unit area of wall was determined by morphometry. In a control group, LA was found to increase exponentially, along with increasing wall thickness D, among arteries from various anatomic sites of patients with greatly divergent ages. The regression curve crossed the x-axis at D = 0.6 mm, showing that arteries thicker than this have an auxiliary circulation by vasa vasorum. The LA was markedly high both in neonates and in patients with cyanotic heart anomaly, ie, in conditions where medial cells were sustained under reduced oxygen supply. Thus, vasa vasorum were shown to elongate their intramural segments in response to the changes of microenvironment in which the medial cells are placed, meeting the demand by the cells for increased supply of oxygen and nutrients.