Abstract
The arterial and venous sides of the microcirculation in the normal human aortic arch have been shown. The arteries originate from the ostium of the innominate artery and the terminal branches of the bronchial arteries. They are distributed to the adventitia and outer 2/3 of the media. The veins originate in the inner 1/3 of the media and drain through the artery wall into irregular adventitial venous plexuses, which are tributaries of the bronchial veins. The terminal arteriovenous anastomosis occurs in the inner 1/3 of the media. No injection medium entered the intima.