Study On The Morphometrical Parameters And Enzymatic Activity Of Digestive Tract In Male Gymnocypris Eckloni Herzenstein

The Gymnocypris eckloni Herzenstein is an important germplasm resource of aquatic wild animals, having the higher economy value. The technologies of artificial breeding and bait for this species have not been well-developed. In this paper, the morphological parameters and digestive enzyme activity of the digestive tract in G.eckloni were studied. These results will provide not only theoretical foundation for its digestive physiology and breeding, but also useful information for its protection and development.The morphological parameters and digestive enzyme activity of the digestive tract in G.eckloni were determined by the methods of anatomy, histology, histochemical and enzymatic technology. The results showed that the G.eckloni digestive tract consists of the oropharyngeal cavity, oesophagus, anterior intestine, middle intestine and posterior intestine. G.eckloni has a S-shape intestine and the intestinal coefficient (IC) was 2.38±0.12 (n= 20). The wall of G. eckloni digestive tract consisted of mucosa, submucosa, muscularis and serosa. All parameters in the oropharyngeal cavity showed significant differences when compared with other digestive organs (P<0.05 or P<0.01). The muscle of oesophagus was well-developed. The height and number of mucosa folds, thickness of submucosa were significantly decreased (P<0.01) from the anterior intestine to the posterior intestine (P<0.05 or P<0.01). The villi of absorptive cells showed the decreased tendency in the height and density from the anterior intestine to the posterior intestine. A lot of pinocytotic vesicles were revealed in the terminal web of absorptive cells in the middle and posterior intestine. According to AB-PAS staining, the density of mucous cells in the digestive tract of G. eckloni was oesophagus> posterior intestine> oropharyneal cavity> middle intestine> anterior intestine. The oropharyneal cavity and anterior intestine were rich in type? and typelV cells, while predominance of type I and type? were in the oesophagus, middle and posterior intestine. Maximal secretion capacity was found in the oesophagus and anterior intestine. The endocrine cells with different shapes occurred only in the intestine whose distribution decreased gradually from the anterior intestine to the posterior intestine, and these cells could be divided into open and close types. Trypsin, amylase and lipase were detected in three segments of the intestine in G.eckloni. Maximum trypsin activity was present in the anterior intestine, and showed a significant decreased tendency from the anterior to the posterior intestine (P<0.01). The amylase activity of the middle intestine was significantly higher than that of the posterior intestine (P<0.01), but the lipase activity of the middle intestine was significantly lower than that of other two segments (P<0.01).In conclusion, the digestive tract of G. eckloni showed the characteristics of omnivorous fishs according to the macro-structure. The oropharyngeal cavity and oesophagus acted principally as a channel for food intake and transport, while the anterior intestine was the major site of digestion and absorption. The last two segments of intestine are rich in pinocytotic vesicles. Different types and densities of mucous cells and endocrine cells were related to the digestive tract functions of this species. Trypsin, amylase and lipase observed in the intestine indicated an important role for digesting or absorbing protein, lipid and carbohydrate.