Anatomy and histological observation of digestive system in Schizothorax eurystomus

Anatomy, paraffin section and HE staining were used to observe the anatomical characteristics and tissue slice in the digestive tract of Schizothorax eurystomus. The results show that the wall of digestive tract included mucosa, submucosa, muscularis and serosa from inner to outer. The main difference lay in mucosa and muscular layers. The mucosa layer of esophagus was covered with stratified epithelium and abundant goblet cells. The mucosae in the foregut and midgut were obviously lined by a simple columnar epithelium with abundant goblet cells, brush border and lymphocytes. The mucosa of hindgut was composed with pseudostratified columnar epithelium, goblet cells and lymphocytes. From front to back, the number of goblet cells of intestine increased gradually. The muscularis of esophagus and foregut consisted of internal-circular muscle layer and external-longitudinal muscle layer. However, the skeletal muscle and smooth muscle were distributed in muscularis of esophagus and foregut. The muscularis of midgut and hindgut consisted of internal-spiral and external-longitudinal smooth muscle layers. The digestive gland was composed of liver and pancreas, and the pancreas was diffuse in the liver. The hepatic lobule was unconspicuous. In conclusion, the histological structure of digestive system of S. eurystomus is related with its function and feeding habit.