Re Gape Of Fish On The Study Of Gastrointestinal Histology And Immunohistochemistry

The structure of the digestive tract in Schizothorax davidi was studied by the methods of morphology. The results are as follows: Schizothorax davidi with the strong barbel and lips has the tubifrom-like mouth which can contract;The gill raker arranged sparely is big and strong;The esophagus having well-developed plicamucosa is stout and short;The gut is short. The height of the intestinal plicamucosa decreases gradually from the anterior intestion to the posterior one. The circular muscularis of the foregut and the hindgut is thicker than that of the midgut. The epithelial cells of oropharyneal cavity and esophagus of Schizothorax davidi are tightly linked together by many interdigitations and desmosomes. The villus-like protrusions are appeared on the surface of the superficial epithelial cells in oropharyneal cavity and esophagus. The absorptive cells of the fore intestine carry many long and closely packed microvili and contain many mitochondria,rough and smooth endoplasmic reticula and well-developed Golgi complexes. The microvili in the absorptive cells of the hind intestine are stout and sparse. A lot of pinocytotic vesicles occure in the terminal web of the absorptive cells of the hind intestine. There are a few apoptotic cells in the intestinal mucosa, whose nucleus and cytoplasm exhibit obvious morphological changes. The mucous cells in the digestive tract of Schizothorax davidi can be classified into 4 types:type I, type II, type III, type IV. The oropharyneal cavity and the esophagus are rich in type II cells, the foregut in type I cells, the midgut in type III and type IV cells, the hindgut in type II cells. The endocrine cells with different shapes occurred only in the intestine whose distribution decreases gradually from the anterior intestine to the posterior one. G cells are only distributed in the fore and middle intestines, being most in the fore intestine(32. 51 ± 3. 03 number/mm~2). Ec cells are located in the different parts of intestine, being most in the fore intestine (24. 25±3. 05number /mm2), less in the hind one (23.56 ± 3.84 number/mm~2) .lowest in the middle one (15. 51 ± 2. 85number/ mm~2 ) . Som cells are occured in the whole intestine, being most in the fore intestine (22. 53 ± 3. 67number/mm~2);Glu cells are appeared in the intestine and have the higest frequency in the fore intestine (16. 50±2. 21 number/mm~2) . Conclusion: the digestive tract of Schizothorax davidi shows the characteristics of carnivorous fishs. The absorptive functions decreases gradually from the anterior intestion to the posterior one. The foregut plays an important role in absorptive functions. The absorptive cells of the fore and hind intestines show characteristics of lipid absorption and strong pinocytosis respectively. The density of the mucous and endocrine cells in the intestine is closely related to the functions of the different segments in the digestive tract. The distribution of G, Ec, Som, Glu cells in the digestive tract of different fishes is dramatically different.