Examining the Stomach Structure and Function in Mudskipper (Periophthalmus waltoni) by Histological and Immunohistochemical Methods

Abstract

Anatomically, the digestive system of oxudercinae lacks a distinct stomach, and that is why this group of fish is classified as stomachless. Since the environment, dietary requirements, and eating habits strongly influence the anatomy of the fish's digestive system, mudskippers (Periophthalmus waltoni) appear to have a stomach due to their carnivorous nature. The present study was undertaken to confirm the presence of stomach in P. waltoni and for this purpose, histological and immunohistochemical methods were used in this study. The results of this study showed that despite absence of an anatomical and distinct stomach, histological point of view the digestive system of this species was divided into 4 distinct parts; esophagus, stomach, intestine, and rectum. The stomach consisted of tubular glands in which the oxynticopeptic cells were present. In an immunohistochemical examination, the observation of the protein channels H+/K+ ATPase and Na+/K+/Cl cotransporter in the membrane of the oxynticopeptic cells confirmed the function of the stomach. In conclusion, the digestive system of P. waltoni is consist of the esophagus, stomach, intestines, and rectum, anatomically. Microscopic evaluation of digestive system indicated that unlike some other species, the Stomach is existed in P. waltoni, but has not any secretion of acid.