Aspectos histológicos, histoquímicos e imuno-histoquímicos do tubo gastrintestinal de Astyanax bimaculatus (Linnaeus, 1758) nos Reservatórios: do Funil, Santa Cecília e Ilha dos Pombos

Abstract

This study aimed to describe the histology and histochemistry of the stomach and gut of A. bimaculatus and analyze the presence of endocrine cells in the gastrointestinal tract (GIT) on the same species in three reservoirs of the Paraiba do Sul River (UHE Funil, UHE Santa Cecilia and UHE Ilha dos Pombos), order to compare the regional distribution and frequency of endocrine cells secreting somatostatin (SOM), gastrin (GAS) and serotonin (5-HT) in specimen of each environment. We used 12 specimens of each reservoir, which are collected using gillnets and sacrificed by hypothermia. After dissection occurred to the immediate removal of GIT. Subsequently, fragments of the stomach and gut were fixed for 8 hours in Bouin liquid and sent to the Laboratory of Histology and Embryology of UFRRJ, where they were subjected to histological processing and histochemical routine with periodic acid + reactive Schiff (PAS) and Alcian Blue pH 2.5 (AB) to posterior the realization of immunohistochemical study. Histologically the stomach of A. bimaculatus showed two distinct regions (glandular and non glandular) and gut was divided into anterior and posterior segment, being the only regions of the stomach and gut PAS reactive to reactive to PAS and AB respectively. In immunohistochemical study of three types of cells immunoreactive (IR) IR studied, only cells to 5-HT were identified in the stomach region (epithelia and glands) and gut. GAS cells to IR and SOM were only detected in the stomach. GAS cells to IR was detected only in the gastric glands. The regional distribution and frequency of endocrine cells varied across regions of the GIT and also among the specimens of each reservoir. It was noted that there was no difference in histological GIT of A. bimaculatus in the comparison of the three reservoirs and that it is compatible with your omnivorous. By immunohistochemistry we found that the regions of the stomach of A. bimaculatus occurred a frequency of almost exclusively three types of endocrine cells studied, which may indicate that this organ is the main site for digestion of food of this species, being also observed a similarity in the amount and distribution of these cells in the GIT of specimens coming from the different reservoirs.