Comparison of the Histological Changes in the Digestive Tract of Lake Van Fish (Alburnus Tarichi Güldenstädt, 1814) During Reproductive Migration

Abstract

Van Lake is the largest soda lake in the world. The Van Fish, which is a single fish species has adaptedto the extreme conditions of the lake. The fish is anadrom and migrates from the lake to fresh water forreproduction and returns to the lake again. In the present study, the histological structure of the digestive tract ofVan Fish in the lake and the freshwater environment was investigated. It was observed that the digestive tractwas composed of a short oesophagus, a stomach-like structure, anterior intestine and posterior intestine,respectively. It has been determined that there is no obvious stomach structure as in some other fish. The digestivetract of Van Fish taken from fresh water and lakes were stained with Hematoxylin-Eosin, Periodic Acid Schiffand Alcian Blue pH 2.5. When the cross sections of digestive tracts were examined, it was observed that itconsisted of mucosa, submucosa, muscularis and serous layers. Muscularis mucosa layer was not observed inthis species. It was determined that the mucosa layer consisted of simple columnar epithelial cells, connectivetissue and blood vessels of the submucosa layer, muscularis layer along the digestive tract, both transverse andlongitudinal smooth muscle cells, and the serous layer were composed of thin connective tissue. It has beenfound that the thickness of these layers varies according to the parts of the digestive tract. Goblet cell thatcontaining neutral and acidic glycoconjugate, sizes, number, and distribution in the mucosa layer were changedaccording to the parts of the digestive tract. It was observed that the Na+, K+, ATPase (NKA) containing cells,which play a role in ion regulation, are densely in the posterior intestine and rectum of the samples taken fromthe lake adapted fish. It was determined that the digestive tract of Van Fish showed similarity to the family ofCyprinidae.