Histological aspects of the digestive tube of the sagüiru, Steindachnerina notonota (Miranda Ribeiro, 1937) (Pisces, Curimatidae), of Ceará Mirim River, Rio Grande do Norte, Brasil

Abstract

In the work, histomorphological aspects of the digestive tube of the saguiru, Steindachnerina notonota, are observed, providing subsidies to the understanding of its alimentary habits and adding informations about the species. Segments of the esophagus, stomach and intestine of twelve saguiru specimens with 9.4 cm of average standard length, from the Ceará Mirim River, were collected in October and November 2001. Anatomical and histological methods were used, as Hematoxilineosin and Periodic acid-Schiff. The results show that the digestive tube of the saguiru is similar to that found in ilyophagous species, being constituted of a short esophagus, a mechanical gizzard like stomach; and a winded and long intestine, which is approximately 9.5 times longer than the fish. The following histological aspects are worth of pointing out: the esophagus has a bistratified epithelium with predominance of PAS positive and neutral secreting cells, and a submucosa rich in adipose cells; the stomach presents three distinct regions - the cardiac region, containing many tubular gastric glands, the middle region, with deep gastric crypts and few glands, and the pyloric region, devoided of gastric glands and with a well developed muscle layer; the caeca has a morphology similar to that of the intestine, however with bigger and longer folds in the mucosa; the intestine has a thin wall, with a mucosal layer more developed than the muscular one. All the digestive tube is covered by a serous tunic.