Some Segmental Features on the Structure of the Aortic Wall of the Dog

Abstract

Structural features of segmental parts of the aorta of the dog were studied by light microscopy (LM) and scanning electron microscopy (SEM). The variability in the wall architecture composition and vascular thickness of the ascending (T2-3 level), thoracic (T7-8 level) and abdominal (L6-7 infrarenal level) segments of the aorta was analysed. Morphological features such as presence of intimal folds, pattern of the medial myoconnective components with segmental variations in the number of elastic lamellae, whose relative number was higher in the thoracic aorta (ascending and descending parts), compared with the abdominal aorta, and a network of connective (stromal) elements formed by elastic and collagen lamellae and fibres in the adventitia were observed. The results were discussed on a histophysiological basis, because small but significant segmental differences had been characterized in the aortic wall structure of the dog.

Structure and Histophysiological Considerations on the Arterial Wall of the Dog

“…1), such as was described in other mammal, also including the aorta of the dog (Viegas et al, 2001;Orsi et al;Mello et al, 2004Mello et al, , 2007Mello et al, , 2009. Inside the ascendant aortic wall a luminal blood flow was observed which shows a vortex pattern as a consequence of the left ventricular systolic pressure (Melbin & Detweiler, 1998).…”

“…1), similarly described in other mammals (Viegas et al, 2001;Mello et al, 2004Mello et al, , 2009, could be considered the radial distension verified in aortic wall during the impact of the systolic pressure of the heart left ventricle (Tindall & Svendsen;Sthebens, 1996). Apparently, the interrelations established among smooth muscle cells and connective lamellae and fibers were prevalent, mainly disposed as meshwork into the aortic medial and adventitial layers (Wolinsky & Glagov, 1967;Tindall & Svendsen;Clark & Glagov;Hass et al;Awal et al;Viegas et al, 2001;Orsi et al;Mello et al, 2004Mello et al, , 2007Mello et al, , 2009. Those intermingled connections established between mural elastic and dense collagen fibers and lamellae, and also with smooth muscle cells, help guarantee the aortic mural integrity, besides the alternative mechanic impacts suffered by the aortic wall during cardiac cycle (Sthebens;Melbin & Detweiler;Mulroney & Meyers, 2010).…”

“…Also observed on the mural aortic architecture of dog was the presence of membranous elastic tissue also disposed as lamellae and fibers (Song & Roach, 1985;Orsi et al). The predominance of aorta elastic tissue in mammals is accomplished by interconnections among elastic lamellae and connective dense lamellae throughout connective dense fibers.…”

“…the vertebral and external iliac arteries, presented a relative major number of smooth muscle cells in their parietal coats (Viegas et al, 2004;Martini et al, 2009;Tortora & Grabowisky, 2012). Perhaps, some papers suggested presence of a mixed structure from the abdominal part of aorta, in which equilibrium in the mural distribution of smooth muscle cells and connective matrix components were verified, with a minor number of elastic lamellae and fibers occurring (Viegas et al, 2001;Orsi et al, 2004;Mello et al, 2004Mello et al, , 2007Mello et al, , 2009). This last distal aortic wall composition apparently supports one of the causes for abdominal aortic aneurysm pathology (MacSweeney et al, 1992;Henney et al, 1993).…”

“…The predominance of aorta elastic tissue in mammals is accomplished by interconnections among elastic lamellae and connective dense lamellae throughout connective dense fibers. Complex networks were seen, including smooth muscle cells intermingled with elastic and connective dense lamellae and fibers, mainly disposed into the aortic medial layer structure (Tindall & Svendsen, 1982;Clark & Glagov, 1985;Hass et al, 1991;Awal et al, 1995;Viegas et al, 2001;Orsi et al;Mello et al, 2004Mello et al, , 2007Mello et al, , 2009). …”