An X-ray Microscopic Study of the Vasa Vasorum of the Normal Human Aortic Arch

The arterial and venous sides of the microcirculation in the normal human abdominal aorta have been shown. 2. The arterial vasa originate extramurally from the lumbar and mesenteric arteries to be distributed to the outer two thirds of the media. 3. The venous vasoriginate in the inner third of the media, and drain through the aortic wall into circumferential adventitial veins, which are tributaries of the lumbar veins. 4. The capillary-venule bed lay in the inner third of the media. 5. No injection medium entered the intima.