Anais do I Simpósio Brasileiro de Morfologia Comparada de Vertebrados

The aim of this study was to characterize the morphology and histochemistry of the digestive tract of three small characid fish (Psalidodon bifasciatus, P. aff. gymnodontus and Bryconamericus ikaa) from streams in Iguaçu River basin. We examined the gross anatomy of ten individuals of each species and made histological cuts of the digestive tract, stained with Toluidine Blue and PAS and analyzed using light microscopy. Characid fish species had some differences in their anatomical digestive traits, but with histological structure similarities. Species had a short and tubular esophagus that opens in a stomach, a J-shaped saccular organ, with a thick wall and consisted of cardiac, fundic and pyloric regions. There were four main intestinal loops and presence of pyloric caeca in the anterior region. Bryconamericus ikaa presented lower number of pyloric caeca and shorter intestine length. In contrast, P. bifasciatus had great number of pyloric caeca and longer intestine. All species presented similar histological structure of wall of the digestive tract composed of four layers: mucosa, submucosa, muscular, and serosa. In general, mucosa was composed of columnar epithelium with presence of goblet cell in esophagus and intestine. Specifically, goblet cells seem more abundant in the posterior region of the intestine. Submucosa layer was thick in esophagus and decreased in stomach and intestine. Gastric glands were abundant in cardiac and fundic region of stomach. Muscularis, mainly circular layer, was well developed in esophagus and stomach (pyloric region) in comparison with intestine. Both anatomical and histological traits can be associated with omnivory recognized for these species. These first results about digestive trait of these species could be useful to answer further questions about ingestion, digestion, absorption and assimilation of food.