MORPHOLOGICAL AND HISTOCHEMICAL OBSERVATIONS ON THE OESOGASTER OF THE DOMESTICATED AFRICAN CATFISH (CLARIAS GARIEPINUS BURCHELL, 1822)

Abstract

Summary Ikpegbu, E., D. N. Ezeasor, U. C. Nlebedum & O. Nnadozie, 2013. Morphological and histochemical observations on the oesogaster of the domesticated African catfish (Clarias gariepinus Burchell, 1822). Bulg. J. Vet. Med., 16, No 2, 88−95. The morphology of the intermediate region between the adult caudal oesophagus and cardiac stomach usually referred to as oesogaster was investigated in the farmed African catfish. This study was carried out to fill the dearth of information from available literature, especially the anatomic features that relates to the adaptation of this species to restriction in concrete tanks. The oesogaster was characterised by covering of PAS positive stratified mucous epithelium and gastric gland within the lamina propria. It contained a combination of the epithelia seen in both oesophagus and stomach. The gastric mucosa had the presence of oxyntopeptic cells in the lamina propria but these cells were absent in the region with oesophageal-like epithelium. The tunica muscularis in this transition region contained skeletal muscle fibres. The serosa was of simple squamous cells. The presence of the oesogaster in a stomach possessing fish suggests that the fish is adapting to fast deglutition in an intensive rearing environment necessitating the need for extension of esophageal mucosubstances which will help lubricate the feed further in the stomach, increase surface area for gastric digestion and possibly add extra carbohydrate to the fish diet, and buffer the effect of acid from the oxyntopeptic cells of the gastric gland.