The present study was carried out using both light and electron microscopies to investigate the micro structure of bursa of Fabricius in turkeys. Tissue samples were obtained from 20 turkeys at I month old were provided from Bolca Turkey Company, (Bolu, Turkey). The microscopic structure of bursa of Fabricius was composed of tunica mucosa, tunica muscularis, and tunica serosa. The tunica mucosa was made up by the plicae which projected through the lumen of bursa of Fabricius. The lamina epithelialis was comprised two different epithelium which were interfollicular epithelium (IFE) and follicle associated epithelium (FAE). Microvilli were seen on the apical surfaces of interfollicular epithelium cells which contained mucous granulles in their cytoplasm. Microfolds were detected on the apical surfaces and many vacuoles and vesicles in the cytoplasm of the follicle associated epithelium cells. The follicle associated epithelium was supported by the supporting cells which infolded into the medulla and formed lamellated epithelial bodies. The plicae of bursa of Fabricius contained lymphoid follicles which were divided into cortex and medulla. Lymphocytes, lymphoblasts, reticular epithelia] cells (REC) and macrophages were observed in the cortex and medulla. Although many secretory dendritic cells (SDC) were seen in the medulla, they were not seen in the cortex. Tonofibrils and lipid droplets in the cytoplasm of the reticular epithelial cells which were abundant in the medulla and rare in the cortex were observed. Many alpha naphtyl acetate esterase (ANAE)-negative and a few ANAE-positive cells were detected in the cortex and medulla of the lymphoid follicles. Plasma cells were also detected beneath the interfollicular epithelium and at the interfollicular region, and pyroninophilic cells were seen in the lymphoid follicles as well.
