Descrição anatômica dos ramos arteriais da aorta torácica e abdominal do quati (Nasua nasua) (Carnivora, Procyonidae)

Aortic branches and rete mirabile of the limbs of two-toed sloth (Choloepus didactylus)

Choloepus didactylus has reduced metabolism and difficulty in thermoregulation owing to its low body mass, and there are few studies related to the vascularization of abdominal and thoracic organs in this species. Therefore, we macroscopically described the arteries that comprise the aortic arch, thoracic aorta, and abdominal aorta. Six specimens were used, and their arterial systems filled with red latex before fixation in 10% formaldehyde, and fragments of the rete mirabile were processed for histological analysis using light and scanning electron microscopy. In these species, the aortic arch had two branches: the brachiocephalic trunk and left subclavian artery. The initial portion of the abdominal aorta presented four different ramifications, besides to the peculiarities of the adrenal, renal, and iliac arteries. Microscopy of the rete mirabile revealed a muscular artery surrounded by smaller muscular arteries, veins, nerves, and lymphatic tissue joined by connective tissue. Thus, the data obtained have clinical and surgical importance, with applicability in procedures involving vascularization of the thoracic and abdominal organs. We suggest that the rete mirabile is an efficient thermoregulatory structure because it allows the accumulation of blood and the countercurrent heat exchange, as there is no blood mixing.

Collateral aortic branches in the collared peccary (Pecari tajacu Linnaeus, 1758)

The determination of arterial vascular distribution patterns can contribute to more detailed knowledge on arterial systems. In this context, the aim of the present study was to describe the collateral aortic branches in the collared peccary, aiming to define a standard model for this species, providing information through comparative anatomy for analysis of some evolutionary aspects of the order Artiodactyla. Ten young male animals were employed. The vascular system was washed with a saline solution and then perfused with Neoprene 450 latex coloured with red or yellow pigment, followed by collateral aorta branch dissections and analyses. The contrasted digital radiography technique was applied to two animals, which were initially perfused with a barium sulphate solution (1 g/ml) and Neoprene 450 latex at a 1:3 ratio, and subsequently, the digital radiographic examination was performed. The aortic arch of the collared peccary emitted the brachiocephalic trunk and the left subclavian artery, while eight symmetric pairs of dorsal intercostal arteries originated from the thoracic aorta. The abdominal aorta, in turn, exhibited the celiac, cranial mesenteric, renal, caudal mesenteric, testicular, external iliac, internal iliac and sacral arteries as the collateral branches in all studied animals. Therefore, no relevant variations were observed regarding the arrangement of the arterial distribution of the aorta, thus suggesting a static standard model in the collared peccary.

Ramos do arco aórtico e da aorta torácica em bicho-preguiça (Bradypus variegatus)

RESUMO As preguiças são mamíferos arborícolas, bem específicos quanto aos hábitos e à morfofisiologia. Essa condição faz delas ainda mais vulneráveis aos impactos ambientais. Com o objetivo de fornecer informações que auxiliem na clínica médico-cirúrgica desses Xenarthras, realizou-se um estudo do arco aórtico e da artéria aorta torácica, a fim de se identificarem seus principais ramos. Foram utilizados 10 animais da espécie Bradypus variegatus, sendo uma fêmea e três machos submetidos a dissecação, por meio da qual foram obtidas medidas de diâmetro e comprimento dos vasos, enquanto três fêmeas e três machos destinaram-se à técnica de radiografia digital com contraste. Constatou-se uma sintopia uniforme do arco, bem como da porção descendente da artéria aorta no tórax. No entanto, a topografia difere consideravelmente. Com base nos ramos, percebeu-se, independentemente do sexo, uma maior variação naqueles originados do arco e dos que emergem da artéria aorta torácica e irrigam estruturas medianas e do antímero direito do tórax. Foram obtidos valores maiores para o diâmetro das artérias na fêmea do que nos machos e, para o comprimento da artéria aorta torácica, foram encontrados valores correspondentes em ambos. Toda essa variação dos bradipodídeos apresenta diferenças em relação a outros mamíferos.