Ramos aórticos e rete mirabile dos membros locomotores de Choloepus didactylus.

Abstract

Choloepus didactylus, known as two-toed sloths, is found in northern Brazil and Latin America. However, because of the destruction of these animals' habitats, they are found more frequently in urbanized areas in need of veterinary care. This care involves basic knowledge such as anatomy and physiology of vascular systems for the success of clinical-surgical procedures in these species. In this dissertation, we identify and describe the origin of the main aortic branches and the Rete mirabile of the locomotor members of Choloepus didactylus. For this, six specimens of Choloepus didactylus had their arteries filled with latex, dissected and fixed in 10% formaldehyde; also, they had fragments removed for analysis by light and scanning microscopy. In this species, the aortic arch had two branches, the brachiocephalic trunk and the left subclavian artery. The initial portion of the abdominal aorta showed four different branches when compared to the species itself and to other mammals. Moreover, the specimen had peculiarities in the adrenal, renal and iliac arteries. Microscopy of the rete mirabile revealed a muscular artery being surrounded by smaller muscular arteries, veins, nerves and lymphatic tissue, joined by connective tissue. Given the above, Choloepus didactylus has distinct aortic branches when compared to members of the same Superorder. The description of the different ramifications of the initial portion of the abdomen is important in clinical-surgical procedures and has not been shown to be related to the sex or age of the animals. Finally, the rete mirabile is suggested to be a source of blood storage during prolonged muscle contractions and an efficient thermoregulator.