Morfologia do esôfago, estômago e progressão alimentar gástrica de preguiças de três dedos (Bradypus variegatus).

Abstract

The adaptations to the tree folivore diet of sloths are evident soon in chewing. Due to food specialties, sloths have a range of morphophysiological changes in the digestive tract and in agreement with the acrobatic behavior and laterality performed by these Xenarthras, these individuals represent a differentiated group with respect to anatomy and digestive physiology. In view of the above, the objective was to investigate the morphological characteristics of the common sloth digestive apparatus, in order to support the understanding of the digestion of these animals, as well as their feeding behavior, and with that help in the preservation of the species. Seven adult animals were used, in which the esophagus started the larynx dorsal to the left of the trachea, remaining adjacent to it, still in the left antimer, along the entire cervical portion. In the thorax, it crossed the mediastinum, crossing the diaphragm through the esophageal hiatus, reaching the stomach. Histologically, the esophagus followed a peculiar pattern that facilitated the understanding of the animal's digestive apparatus, being this with keratinized mucosa and skeletal striated muscle layer, presenting smooth muscle only in the transitional esophagus-stomach region. The anatomical analysis of the stomach of laziness allowed us to characterize the division into seven compartments: cranial sac, central sac, fundus, caudal sac, diverticulum and pre pilorus I and II. The cranial sac was characterized by the esophageal insertion zone, the first cavity of the stomach being located in the cranial region, deviated from the left. Next, the central bag positioned in the middle region of the animal's body was preceded by the caudal sac, which was positioned in the right antimer. The fundus was located in the central cranial region of the organ so above the diverticulum, which overlapped prepilorus I and II (duodenal insertion). Microscopically, the compartments revealed two distinct patterns: a flat agglutinated stratified keratinized flat tissue fraction and a glandular fraction of mucosa lined with low prismatic glandular epithelial tissue with short pits and long gland formations. Finally, we conclude that the unique configuration of the esophageal tube, combined with the complexity of the stomachs and posture behaviors before and after ingestion, the histological composition and the low metabolic rate infer some of the behaviors peculiar to the sloths of the Bradypus variegatus species, knowledge of food traffic.