ANATOMICAL, HISTOLOGICAL OBSERVATIONS OF DIGESTIVE SYSTEM AND DIGESTIVE ENZYME ACTIVITY IN DISCOGOBIO YUNNANENSIS

The present study investigated the structure and function of the digestive system in Discogobio yunnanensis by morphological, histological and zymologic methods. Results showed that the mouth of D. yunnanensis was inferior, and the digestive tract was composed of oral cavity, esophagus and gut without an obvious stomach. Many taste buds and goblet cells were distributed in oral epithelia. The esophagus was short and thick with abundant goblet cells in the mucous layer. The intestinal index was 5.06±0.61, and the gut was the largest part, which hovered in the body cavity. According to the morphology, the gut with abundant villi was divided into the cranial, middle and posterior parts. Digestive gland was hepatopancreas, and the liver was divided into two parts, with pancreas diffused in. The different digestive parts had diverse digestive enzyme activities. The activities of lipase in different digestive parts ranged as follows: hepatopancreas>foregut>midgut>hindgut, while those of trypsase, amylase and alkaline phosphatase were foregut>midgut>hepatopancreas>hindgut. These results suggest the adaptation of this fish in feeding fixed algaes.