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.