September 16, 2025

Histological and Histochemical Characteristics of the Digestive Tract of Tire Track Eel, Mastacembelus Favus (Hora, 1923) (Synbranchiformes: Mastacembelidae)

ASAkkarasiri SangsawangKasetsart University AVAkapon VanikasambanaSrinakharinwirot University SISonchai IntachaiCenter for Innovation

Key Points

The digestive tract of mastacembelus favus includes pharynx, esophagus, and various stomach regions, reflecting its functional anatomy.
Histological examination revealed that pharynx and esophagus secrete neutral, carboxylated, and sulfated glycoproteins, critical for digestion.
Gastric glands were present only in the cardiac and fundic stomachs, contributing uniquely to the digestive functions of the fish.
The intestinal coefficient of 0.22 strongly indicates that mastacembelus favus is a carnivorous fish, which has implications for ecological understanding.

Abstract

Mastacembelus favus (M. favus) is an important fish for local fisheries in Southeast Asia, however the corresponding microanatomy research has been scared. Therefore, this research was aimed to examine the histological and histochemical characteristics of the digestive tract of M. favus. The digestive tracts of ten adults M. favus from Phatthalung province, Thailand, were obtained using a paraffin technique process and stained with hematoxylin and eosin, periodic acid Schiff’s, alcian blue pH 2.5 and AB pH 1.0. The findings explained that the digestive tract was consisted of pharynx, esophagus, stomach (cardiac, fundic and pyloric stomachs), pyloric caeca and intestine (anterior, middle and posterior intestines). The secreting-mucous and goblet cells of pharynx and esophagus was positively stained with PAS, AB pH 2.5 and pH 1.0, whereas the epithelium of stomach was only stained with PAS. The enterocytes of intestine and pyloric caeca were positively stained with PAS, whereas the goblet cells displayed positively stained with PAS and AB pH 2.5. All portions could secrete neutral glycoproteins, whereas only pharynx, esophagus and intestine could provide carboxylated glycoprotein. Meanwhile, sulfated glycoprotein was secreted by pharynx, esophagus and pyloric caeca. The gland was observed only in cardiac and fundic stomachs and its epithelium cell only secreted neutral glycoprotein. The wall of all portions surrounded by smooth muscle layers except for pharynx and esophagus were skeleton muscle. From overall results and intestinal coefficient (0.22) could indicate M. favus as a carnivorous fish. The present study may offer valuable profiles for investigating a comparative anatomy, ecology, pathology and future aquaculture. HIGHLIGHTS Intestinal coefficient and histology confirmed favus as a carnivorous fish. Pharynx and esophagus secreted neutral, carboxylated and sulfated Cardiac, fundic and pyloric stomachs secreted only neutral glycoprotein. Gastric gland was in cardiac and fundic stomachs without in pyloric stomach. Pyloric caeca and intestine secreted neutral, carboxylated and sulfated GRAPHICAL ABSTRACT

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