Morphological and histological observation on digestive system of Acrossocheilus yunnanensis

The morphological and histological structure of the digestive system of A. yunnanensis were observed by morphological dissection and paraffin sectioning techniques. The digestive system of A. yunnanensis is divided into two parts: the digestive tract and the digestive gland. The digestive tract consisted of the oropharyngeal cavity, esophagus, intestine and anus, with an intestinal coefficient of 1.52±0.39. The mucosal epithelium of the oropharyngeal cavity and esophagus is a compound flat epithelium and contained goblet cells. The esophageal muscle layer is well developed and consists of skeletal muscle. The intestine is divided into three parts: anterior intestine, middle intestine and posterior intestine. From anterior intestine to posterior intestine, the mucosal folds numbers, mucosal folds height, columnar epithelial cells height, submucous layer and cyclic muscle layer thickness of A. yunnanensis are decreased successively. Meanwhile, the thickness of the longitudinal muscular layer and the number of goblet cells are first increased and then decreased. The digestive gland is divided into the liver and pancreas. The liver is divided into two lobess, the pancreas is mainly distributed in the mesentery, and the gallbladder was oval in shape and larger in size. It suggested that the histological characteristics of the digestive system of the A. yunnanensis were compatible with its food habits, and it was an omnivorous and carnivorous fish.