Bradypus variegatus, vulgarmente conhecida como preguiça comum, pertence a um grupo individualizado de mamíferos, com peculiaridades morfológicas e biológicas já descritas, porém, pouco se sabe sobre questões estruturais do seu trato digestório, incluindo a morfologia do esôfago. Diferindo dos mamíferos em geral quanto ao trajeto completo do órgão, o esfíncter esofágico cranial localiza-se dorsalmente à laringe, desviando à esquerda da traqueia, mantendo-se adjacente a ela, ainda no antímero esquerdo, ao longo da porção cervical. No tórax, seguiu pelo mediastino, atravessou transversalmente o diafragma através do hiato esofágico, alcançando o estômago. Histologicamente, apresentou o mesmo padrão tecidual ao longo das três porções, destacando-se a presença de três camadas musculares, adensando na porção torácica, e na adventícia cercada pela cadeia nervosa simpática, adjacente à região cárdica. Essas características histológicas conferem ao esôfago dessa espécie arquitetura peculiar, que pode explicar o comportamento de deglutição destes indivíduos frente aos seus hábitos posturais.

Fermentative herbivorous animals have peculiar conformations of the digestive system. It is known that B. variegatus obtained the capacity for evolutionary adaptation, due to their ecology and eating habits. However, despite the literature on feeding management for this species, there is a lack of published information regarding its gastric morphology, and such information would support a better understanding on the diet and digestion of these individuals. We found seven gastric compartments, which histologically revealed three distinct patterns: an aglandular keratinized fraction (mechanical stomach) and two glandular fractions, one a mucus secretor and the other one composed of acid secreting cells (chemical stomach). With these evidences we understand that these individuals have gastric resemblance to ruminants, with some inherent peculiarities of this species, including the transit of the bolus.

The wall of the diaphragm can be affected by changes caused by physical trauma, allowing the passage of viscera between the abdominal cavity and thoracic cavity, thus reducing the space for pulmonary expansion, leading to the formation of hernia and possible death. Thus, we aimed to characterize, size and determine the topography of the diaphragmatic muscle in the Southern Tamandua, since clinical and surgical activities in wild animals have become a reality more and more present in veterinary medicine. We used six adult animals, x-rayed and dissected, followed by collection of fragments of muscular portions for histological analysis. Initially we observed that the animals presented 17 thoracic vertebrae, 3 lumbar vertebrae and 5 sacral vertebrae. The diaphragm was conformed by three segments: sternal, costal and right and left diaphragm pillar, with presence of tendinous centre that housed the passage of the caudal vena cava, called foramen of the caudal vena cava. Dorsally to the tendinous centre, already in the muscle portion, we located the esophageal and aortic hiatus. These findings, as well as the microscopic, were equivalent to that found in the general literature also, corroborating with descriptions already carried out in other mammals' diaphragms.

Behavioral intelligence among non-human primates is a somewhat puzzling area to study, since it is closely linked to the morphology of the central nervous system. However, this morphology is still unknown to science in the case of Saimiri collinsi. As a means of assisting future studies on the social behavior of this species, we analyzed the brains of six adult females from the National Primate Center / Pará, which were sent to the Animal Morphological Research Laboratory at the Federal Rural University of Amazônia after death by natural causes. The animals were fixed in formaldehyde solution (10%) and dissected. The brains were covered externally by the dura mater, with long cerebral hemispheres, although there was a complete absence of gyri. The internal structures which form a part of the telencephalon, diencephalon, midbrain, hindbrain and myelencephalon were identified, with the exception of the mammillary bodies. This condition, when linked to the lissencephaly found in these individuals raises questions about the real learning abilities of this species.