Postnatal development of bursa of Fabricius in relation to humoral Immunity in Keets

The present investigation was carried out on developing guinea fowls from the day of hatch to day 63 with observation made every 7 days interval. The scope of study focused in age associated structural and functional development of the bursa of Fabricius in relation to humoral immunity. Lymphocytes constitute the key component of the immune system. The result of lymphocyte blastogenesis assay is recorded as mean delta optical density (OD). The mean delta O.D. of lipopolysaccharide (LPS) stimulated cultures showed the activity of B-lymphocytes responsible for humoral immunity. Increase in mean delta OD with advancing age of developing Guinea fowls show the increasing responsiveness to LPS stimuli, with high responsiveness between 28 to 42 days of post-hatch life. On histological study, it was observed that bursa was composed of tunica mucosa, tunica muscularis and tunica serosa. Tunica mucosa projected in to the lumen and formed plicae surrounded by pseduostratified columnar epithelium. Each plica were completely filled with follicles and separated by connective tissue. Greater size and number of follicles and maximum increase in basophilic character of bursal follicles was observed between 28 to 42 days of post-hatch life. From the findings of lymphocytes stimulation test and histological study it is clear that humoral immune system develops rapidly during 28 to 42 days of post hatch life in developing Guinea fowls.