Author(s): Anand Singh, SP Singh, MM Farooqui, Archana Pathak, Abhinov Verma and Amit Vishen

Abstract: The study aimed to provide the basic findings about the age-related involutory changes, the study was conducted on the bursa of Fabricius of thirty Chabro birds. The birds were selected after hatching irrespective of sex and divided into five groups (0, 30, 60, 90 and 150) days of age. The bursa of Fabricius was a sac-like structure connected to the dorsal wall of the proctodeum of the cloaca by a small stalk. Histologically, the wall of the bursa of Fabricius was comprised of three basic layers tunica mucosa, tunica muscularis and tunica serosa. The tunica mucosa consisted of lining epithelium and lamina propria. The epithelium covering the plicae were divided into two types viz, follicle associated epithelium (FAE) and the interfollicular epithelium (IFE). The epithelium was made up of pseudostratified columnar ciliated epithelium. The lamina propria filled with lymphoid follicles of different shape and size. The tunica muscularis consisted of an outer circular and inner longitudinal smooth muscle layer. The outermost tunica serosa was thin. The involutory changes started from the 3^rd group. Depletion of the lymphocytic population from the periphery of the cortex, medulla and separation of cortex from adjacent follicles were noticed at the beginning of involution. An increased convolution of the inter-follicular epithelium (IFE) observed during involution from 3^rd group onwards. Fatty changes in the sub epithelial and interfollicular connective tissue and formation of the epithelial cyst, area of epithelial attenuation, vacuolations, folding and detachment were found over the plical surface and in the interplical areas. In the 5^th group, the plical epithelium was difficult to identify.

DOI: 10.33545/26174693.2024.v8.i6Sj.1405