The expression patterns of gastrin(Gas),β-endorphin(End).somatostatin(Ss),glucagons(Glu),and 5-hydroxytryptamine (5-HT)cells in the duck bursa of Fabricius were studied by the immunohiswchemicai method associated with image analysis.The resuhs showed that the Gas-positive cells with high intensity wrte seen in the follicle-associated epitllelium (FAE),the End with medium intensity in the interfollicular epithelium,the End,Gas and 5-HT with medium or high intensity in the cortex of lymphoid follicles.and the Gas with high intensity in the medulla of lymphoid follicles.Both SS and Gh showed negative reaction.The pre-sent results demonstrated that the Gas,End and 5-HT cells are differentially expressed in the different parts of the duck bursa.The positive cells distributed in the cortex of lymphoid follicles might favour exerting their influence via an endocrine, autocrine or paracrine pathways on the development of B cells.

Objective: To investigate the influence and mechanism of zinc toxicity on the stucture and function of immune organs in ducks. Methods: By establishing the pathological model of zinc toxicity in ducks, some immunological methods, light and electron microscopes were used to check the changes in the stucture and function of immune system. Results: (1) The body weight of ZT group was significantly lower than that of ZC group after 3 weeks (P