Morphological, histochemical and ultrastructural studies of the digestive tract of the genus Leporinus (Characiformes, Anostomidae)

Abstract

Studies on the morphological characteristics of the digestive tract, associated with the processes of digestion and absorption of nutrients, are essential for understanding the physiology and nutrition of fish, assisting in the planning of commercial diets to provide better management and success in farming. The objective of this paper is to describe the gut of three species of the genus Leporinus (L. elongatus, L. and L. obtusidens macrocephalus), to support the creation on farms. The Leporinus genus is composed of fish omnivores, which have characteristics favorable for breeding in fish farms, such as ease of reproduction in captivity and easy acceptance ration in adulthood. But the creation of these species is still rudimentary due to lack of information and proper nutrition. For this study, twenty specimens of each species will be collected in the Paraná River. The animals will be slaughtered in solution of benzocaine. Then a longitudinal incision is made in the ventral region of the animals for analysis and removal of the organs of the digestive tract. Macroscopic analysis will be undertaken involving identification and morphometry of organs. For histological tissue fragments are fixed in modified Karnovsky solution, undergoing routine inclusion in historesin and stained with toluidine blue 1%, Masson's trichrome and HE. For transmission electron microscopy, the fragments will undergo routine inclusion in Araldite resin, the cuts will be mounted on copper screens and contrasted with uranyl acetate and lead citrate for analysis of ultrastructural features of the epithelial lining of the digestive tract. For histochemical analyzes fragments of tissues are fixed in Bouin's solution and intended for routine inclusion in Paraplast. Histological sections are subjected to histochemical reactions for detection mucossubstâncias with periodic acid-Schiff (PAS), Alcian Blue (AB pH 1.0 and pH 2.5) and AB (pH 2.5) + PAS. This study aims to contribute new knowledge regarding the morphofunctional aspects of the digestive tract of omnivores and provide support for development of national aquaculture based on these species. (AU)