Morphology and histochemistry of the bursa of Fabricius in White Pekin ducks

Abstract

The morphology and histochemistry of the bursa of Fabricius of White Pekin duck was studied using 10 apparently healthy 2 month old birds. The bursa could be seen as a smooth, yellow elongated blind sac like structure with tapering apex. Its inner luminal surface was plicated with 2 large well developed plicae on the ventral aspect and about 5-6 smaller folds all round the circumference. Histologically the wall of the bursa was divided into 3 tunics. The outermost tunica serosa, enveloped the entire organ. The middle muscularis, consisted of an outer circular and inner longitudinal layer of smooth muscle fibres with blood vessels in between. The inner most tunica mucosa consisted of pseudostratified lining epithelium and lamina propria filled with lymphoid follicles. Each follicle consisted ofan outer thin cortex and inner large medulla separated by a layer of undifferentiated epithelial cells with a distinct basement membrane. Lymphoblast, lymphocytes and macrophages formed the cellular component of the follicle. The interfollicular and subepithelial connective tissue was made up of collagen and reticular fibres with a few elastic fibres. The cellular component in it included plasma cells, eosinophils, mast cells, macrophages and fat cells. The lining epithelial cells of bursal mucosa revealed positive reaction to Schiff's reagent, metachromasia, intenseacid phosphatase and moderate alkaline phosphatase activity.