Study On The Structure Of Gut-associated Lymphoid Tissue And Pathological Changes Of Ducks Infected With Eimeria Tenella

In this experiment, The structure of gut-associated lymphoid tissue(GALT) of semi-muscovy ducks were studied by light, scanning electron microscope and transmission electron microscope. The Function of gut-associated lymphoid tissue(GALT) were studied by using different tracers(trypan blue, horseradish peroxidase ). The pathological changes of ducklings infected artificially with Eimeria tenella were examined using routine pathological methods.The results suggest that the GALT of semi-muscovy duck ware distributed mainly in the small intestine, GALT distinctly appeared as annular bands at four sites, three sites were at jejunum and one site was at ileum. Histologically, the GALT of the duck were similar to those of chickens and mammals; The bands were characterized by promiment lymphoid follicles in the tunica mucosa,submucosa,and tunica muscularis. Large numbers of diffuse lymphocytes could also be seen in the lamina propria besides the annular bands; Observation with scanning electron microscope, there were no villus on the mucosa surface of annular bands, mucosa protruded to form tiny folds, tiny folds connected with each other and formed irregular network structure. Observation with transmission electron microscope, typical characteristics of M cells could be seen: The microvillus were short,sparse,and distorted; The terminal web of the M cells was poorly developed compared with that of the absorptive cells; The M cells were connected with adjacent cells by tight junctions and desmosomes; The cytoplasm contained many vesicles; The "pocket" of M cells enfolded one or several lymphocytes or macrophages.After gavaging trypan blue, trypan blue particles were seen in epithelial cells of GALT and kupffer cells of liver; After injecting horseradish peroxidase(HRP) into intestinal cavity, HRP positive reaction products could be seen within the M cell and the intercellular space of lymphocytes. While the absorptive cells were negative. The results show that GALT are capable of uptake of antigens.After infecting with Eimeria tenella , Grossly, the cecum showed enlargement, hyperemia and hemorrhage , Eimeria tenella live in in the epithelial cells and intestinal gland and in lamina propria of the GALT, causing necrosis and sloughing of epithelial cells, edema, hemorrhage and inflammatory cell infiltration in cecal wall. there were no death in infected ducks. The results suggest that Eimeria tenella has pathogenicity to semi-muscovy ducks , but the pathogenicty is very weak.