Morphological, histological, and histochemical study of the gastrointestinal duct and appendices of the mature Alburnus chalcoides of the Caspian Sea

Sampling of adult Alburnus chalcoides was conducted randomly in the Bony Fish (Osteichthyes) Center of Shahid Ansari of Rasht. At first, measurements were made to study the morphology of Alburnus chalcoides and then the gastrointestinal tract of this fish was extracted for histological examination. For histological studies, Hematoxylin-eosin staining (H & E), and to investigate the polysaccharide neutralization, Periodic acid Schiff (PAS), and finally for evaluation of the proteins compounds Bromophenol blue (BPB) were used. In the studies, it was observed that the gastrointestinal tract of this fish included the esophagus and intestines. Esophagus was short and has relatively long mucosal shapes and in the intestine, there were also these mucosal shapes with more space apart. Cyprinidae have not real stomach. In the anterior part of the intestine, shapes are more and deeper but the Goblet cells are seen in the posterior part of the intestine. Goblet cells are also observed in both the esophagus and intestinal areas which showed a positive reaction with PAS due to neutral polysaccharide compounds. Protein compounds in the enterocyte cells of the intestine as well as mucosal cells of the esophagus rarely respond to BPB. Reactions with these two colors were also observed in liver cells and hepatopancreas. The results show that the characteristics there are specific variations of species related to the esophagus and the intestines.