Immunohistochemical study of the digestive tract ofOligosarcus hepsetus

Abstract

AIM:To describe the histology of the digestive tract and to investigate the occurrence of endocrine cells in Oligosarcus hepsetus (O. hepsetus ). METHODS:The digestive tract (DT) of O. hepsetus was divided into esophagus, two stomach regions (glandular and non-glandular) and two intestinal regions (anterior and posterior). These specimens were processed by routine histological techniques and stained with hematoxylin-eosin, Gomori's trichrome, periodic acid Schiff (PAS) and Alcian blue (AB). An immunohistochemical method using avidin-biotin-peroxidase was employed. RESULTS:The esophagus is lined with a non-keratinized stratified squamous epithelium that is reactive to PAS and AB. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells that are reactive only to PAS. The intestine has a simple columnar epithelium with a brush border and goblet cells that are reactive to PAS and AB. Somatostatin, serotonin and cholecystokinin immunoreactive cells were identified throughout the DT. CONCLUSION:This study revealed adaptations for the species' diet and showed that the distribution and relative frequency of immunoreactive cells are similar to those of other fish.

Histochemical and immunohistochemical study on endocrine cells (5HT, GAS, and SST) of the gastrointestinal tract of a teleost, the characin Astyanax bimaculatus

“…It is likely that in A. bimaculatus, another omnivorous species, the thick folds in the stomach had similar function. The mucus-secreting epithelial cells are very reactive to PAS, but not to AB and this findings match others reported elsewhere (e.g., Castro et al, 2003;Hernández et al, 2009;Vieira-Lopes et al, 2013). According to Grau et al (1992), secretion of neutral mucosubstances in the stomach epithelium may be related to the absorption of easily digestible molecules, which can be related to the species feeding habit.…”

“…Several earlier studies used antibodies produced in mammals and obtained consistent results in fishes, proving the affinity of the antibodies (e.g., Ku et al, 2004;Hernández et al, 2012;Vieira-Lopes et al, 2013). According to Langer et al (1979), the cross-reactivity strongly suggests that peptides in teleosts fishes share similar or even identical epitopes with their equivalents in higher vertebrates.…”

“…Simillaly to other teleosts (Hernández et al, 2009;Vieira-Lopes et al, 2013), A. bimaculatus also have a great number of goblet cells in the posterior intestine. Increasing in goblet cells in the posterior region of the intestine may be related to ions and fluids assimilation that occur in this part of the GIT as reported by Petrinec et al (2005).…”

“…However, there is no available information on its digestive physiology, such as the distribution of endocrine cell thought the gastrointestinal tract. These immunoreactive cells play an important role on the regulation and digestion of several aminoacids and glucose during the food processing (Pan et al, 2000a;Vieira-Lopes et al, 2013). Therefore, in the present study, we describe histological and histochemical aspects of the gastrointestinal tract of A. bimaculatus and the regional distribution of endocrine cells in the tract by immunohistochemistry using three types of immunoreactive cells: the serotonin (5-HT), somatostatine (SST) and gastrin (GAS).…”

“…Overall, the histological architecture of the GIT includes a layer of mucussecreting cells, observed by histochemical techniques in various studies of teleosts (Vieira-Lopes et al, 2013). Secretory cells play an important role in lubricating the organ and protecting against proteolytic degeneration and pathogenic microorganisms (Reid et al, 1988).…”