Sketches of the three types of vasa vasorum found in the wall of cow aortae (inspired by Schoenenberger and Mueller [24]). In the Schoenenberger and Mueller study, VVI (a) originated directly from the aorta’s main lumen, and VVE (b) originated from intercostal branches deriving from the main lumen and dived back into the aortic wall. VVV (c) developed in the aortic wall and finally drained into branches of concomitant veins (reprint with permission from [25]).