The three-dimensional architecture of vasa vasorum in the wall of aorta was studied by microcomputer-aided reconstruction from serial sections of wall tissue in two young individuals submitted to autopsy. The outer media was sparsely penetrated by special tunnels containing an arteriole and a venule, which we termed a "vascular cord" due to the broad space between neighboring cords that contained no capillary network whatsoever. A dense venular plexus was found extending along the outer surface of the media, forming a plane of low blood pressure. This characteristic pattern of vasculature appeared to provide an important basis on which to study the way the medial tissues are sustained.