Análise morfológica do trato digestório de peixes-boi marinhos (Trichechus manatus manatus, LINNAEUS, 1758) na Região Nordeste do Brasil

Abstract

Morphological studies of the digestive tract are relevant for the knowledge of biology and understanding of dietary habits in order to increase conservation efforts of the species. Thus, our study aims to analyze macro and microscopically the digestive tract of the Antillean manatee (Trichechus manatus manatus). Samples were collected from 20 animals that dead stranded in the northeast coast of Brazil or died during the rehabilitation process in captivity between July of 1995 to March of 2017. The macroscopic analysis of the gastrointestinal tract was performed from the followup in loco of necropsies of Projeto Cetáceos da Costa Branca (PCCB-UERN). In order to evaluate microscopically, tissues collected during necropsies were fixed with 10% formalin and submitted to routine histological processing, with cuts of 5 μm of tickness, and subsequently submitted to the Hematoxylin-Eosin staining method (H.E.), Verhoeff methodology and periodic-Schiff acid (PAS) methodology. Macroscopically, neonates and adults present the same structures in the digestive tract. Microscopically, in the esophagus, the esophageal glands are absent and there are elastic fibers in the submucosa and between the muscularis externa and adventicia. The stomach has a structure called cardiac gland, which microscopically, presents ontogenetics differencies. In the duodenal ampulla and diverticula, duodenal glands were identified in the submucosa. In the luminal portion of the mucosa layer of the cecal ampulla, colon and retus, stratified keratinized squamous epithelium was observed. The digestive tract of the Antillean manatee of the espécies Trichechus manatus manatus resemble what has been reported about animals from the Order Sirenia, but presenting some histological particularities in more evidence.