1282 Int. J. Morphol., 29(4):1282-1290, 2011. Morphology and Vascularization of the Gastric Compartments in Three-Toed Sloth (Bradypus torquatus Illiger, 1811) Morfología y Vascularización de los Compartimentos Gástricos en Osos Perezosos de Tres Dedos (Bradypus torquatus Illiger, 1811) * L. C. Rezende; * J. M. Monteiro; ** P. Carvalho; ** J. R. Ferreira & * M. A. Miglino REZENDE, L. C.; MONTEIRO, J. M.; CARVALHO, P.; FERREIRA, J. R. & MIGLINO, M. A. Morphology and vascularization of the gastric compartments in three-toed sloth (Bradypus torquatus Illiger, 1811). Int. J. Morphol., 29(4):1282-1290, 2011. SUMMARY: The macroscopic anatomy and vascularization of the stomach compartments of Bradypus torquatus were examined in five animals from the University of São Paulo College of Veterinary Medicine and Zootechny collection. The method included aqueous perfusion of the arterial network, colored latex injection, fixation in formaldehyde (10%) and preservation in Laskovisk solution. Dissections were performed under mesoscopic light and photo documentations were performed for description and data analysis. In these animals, the largest abdominal organ was the stomach, which internally presented the cardiac, fundic and prepyloric regions, subdivided in six compartments (cardiac right, middle and left; fundic; pre-pyloric I and II). The stomach was irrigated by the left gastric and celiac arteries, which are ventral visceral branches of the abdominal aorta. These arteries emerged in the retroperitoneal region and reached the viscera through the mesogastric region, distributed in the large and small stomach curvatures, in the spleen and the pancreas. The primary collateral branches of the left gastric artery are directed to the large stomach curvature, and the celiac artery irrigated the spleen, the pancreas and the small stomach curvature. The vascular pattern differed in some aspects from that observed in the other multi- cavity stomachs of recent vertebrates. KEY WORDS: Digestive tract; Stomach; Celiac artery; Bradypodidae; Xenarthra. INTRODUCTION Complex organisms have developed extremely sophisticated digestive tract models, due to their functional requirements. This system represents an example of how peritoneal serosa and the vascular network became specialized due to the evolution of the types of organs that composed each organism: the pre-stomachs, stomachs, coelom, mesenteries and various mucosal adaptations. Considering the existence of the superorder Xenarthra in Central and South America (Gardner, 2007; Gaudin & MacDonald, 2008) and the particularities of the body design and feeding habit of sloths, it was decided to study the morphology and the stomach blood supply model of Bradypus torquatus. The various mammalian orders exhibit stomachs with extremely variable forms (Leghissa, 1975; Langer, 1984), presenting aspects of dilated pouches in their primitive form, with two curves and derived from the anterior intestine. It is known that various forms of the gastric compartments are specialized to fulfill specific requirements of animal digestion, depending on the animal’s manner of feeding (herbivore, carnivore or omnivore). Furthermore, digestion, as well as the storage and expulsion of excrement, require coelom and mesentery adjustment, including that related to the blood supply (Grassé, 1965; Garcia & Leal, 2003; Hildebrand & Goslow, 2006). To guarantee the oxygen and glucose supply, the arteries derived from the celiac trunk and the cranial mesenteric are emphasized to provide nutrition to the stomach, spleen, pancreas and the anterior and middle intestines (Grassé, 1955; Moore & Persaud, 2008). Some of these vessels were described in rodents and chelonians (Rodrigues et al., 2003; Culau et al., 2008). Studies on digestive tract morphology in Xenarthra refer to the morphology and vascularization of these structures without specifying aspects of the origin, route, destination or domain territory of the arteries destined for gastric compartments (Britton, 1941; Grassé, 1955; Langer, 1984; Foley et al., 1995; Diz et al., 2006; Souza et al., 2010). * Departament of Surgery, Veterinary Medicine College and Zootecny, University of São Paulo, Brazil. ** Laboratory of Mesoscopy, Faculty of Medicine, University of Brasília, Brazil.