Topologic distributions of vasa vasorum and lymphatic vasa vasorum in the aortic adventitia – Implications for the prevalence of aortic diseases

Recent Developments in Vascular Adventitial Pathobiology

“…They are in close proximity to the arterial VV and appear to be, in contrast to the arterial VV, more dense in the infrarenal abdominal aorta. 23 Nerve Supply in the Adventitia Tissue perfusion and vascular resistance are regulated by vasoconstriction and vasodilation of arteries and arteriolar networks through SMC contractility. The processes involved are as follows: i) molecules secreted by ECs, which have either vasoconstrictive or vasodilatory activity; ii) perivascular innervation in the adventitia 24 ; and iii) paracrine influences from cells in the PVAT, such as adipocytes acting directly on SMCs or via ECs to regulate vasomotion.…”

“…The amount of the adventitial VV differs along segments of the aorta, being more dense in the aortic arch, becoming less dense in more distal segments, and least dense in the infrarenal aorta. 23 Because the prevalence of aortic disease varies at different segments of the aorta, these differences may be an important factor in the predisposition of disease. For example, atherosclerotic aneurysms are at least three times more frequent in the abdominal aorta in comparison to the descending thoracic aorta.…”

“…45 Furthermore, almost all abdominal aortic aneurysms (AAAs) occur in the infrarenal region of the aorta in humans. 23 The adventitia appears to be important in the pathogenesis of AAAs, at least in part during initiation and during the progression of aneurysm formation. Early macrophage infiltration of adventitia is seen in AngII-induced murine aneurysm.…”

“…Because approximately 65% to 70% of cases of aortic dissection occur in the ascending and descending thoracic aorta, it is postulated that the dense distribution of VV in this area of the aorta may make it more likely that a rupture and hematoma occur in the VV, leading to a dissection. 23 However, neither the frequency nor the nature of the rupture is known. This proposed pathogenesis may, however, help explain aortic dissections where no internal tear of the intima-media is found.…”

Increased telocytes involved in the proliferation of vascular smooth muscle cells in rat carotid artery balloon injury

“…There was considerable controversy about the stem cells/progenitors of VSMCs, and the exact source, role and properties of these cells remained unclear. More and more studies reported that components of the adventitia participated in a wide range of vascular diseases (Majesky, 2015;Sano et al, 2016;Wang et al, 2016). In this study, TCs were observed to be located in the tunica adventitia.…”