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MY THESIS...
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Thesis Abstract Name : Rajesh Kumar Banga Advisor : Dr. G. K. Singh (Prof. and Head) Major : Veterinary Anatomy Minor : Veterinary Pathology Thesis Title : “ONTOGENY OF LYMPHOID ORGANS CHICKEN EMBRYOS (GALLUS DOMESTICUS)”.
The present study was conducted to investigate the gross morphological, histoarchitectural and histochemical development of the lymphoid organ (thymus, bursa of Fabricius and spleen) in relation to the functioning of humoral and cell mediated immunity in 6, 11, 14, 16, 18 and 21 day old chicken embryos. Thymus was having highest weight and size, among all the three lymphoid organs studied, followed by the bursa and spleen. Histologically, thymus at 14 day was a loose mass of epithelial cords. It was divided into lobules at 16th day, and by 21st day of incubation thymic lobules were differentiated into outer darker cortex containing lymphocytes and inner lighter medulla. Bursa at 11th day was not having plicae, but by the 14h day plicae were developed with initiation of formation of epithelial buds. With further advancement in age of embryo epithelial buds increased in size and number, with more number of lymphocytes in them. At the 21st day bursal follicles were developed with reticular fibers and collagen fibers encircled around them. Bursal follicles were not divided into cortex and medulla by the 21st day of incubation. Spleen, at 6th and 11th day was a mass of mesenchymal cells and some sinusoids, containing RBC’s and at 14th day had venous sinuses lined by littoral cells and few arterial blood vessels.
At the 16th day the reticular fibers surrounding the blood vessels extend into the splenic mesenchyme. Thereafter, these fibers proliferated in stroma and became very extensive by the 21st day. Arterial blood vessels also increased in number with the age of embryo. Histochemically, activity of acid phosphatase was present in thymus at 18th and 21st day and cholinesterase activity at 18th day only. ATPase activity was also observed at 21st day. In bursa activity of acid phosphatase was more at 21st day than 18th day. Cholinesterase activity was observed only at 21st day. PAS positive material was found in the epithelium of plicae at 18th and 21st day. In spleen the activity of acid phosphatase was seen at 18th and 21st day and cholinesterase at 16th, 18th and 21st day. In Immunological studies, both the T-and B-lymphocytes were found to be responding to the mitogenic stimulation, in lymphocyte blastogenesis, at 21st day. IgG type of immunoglobulins were found in the blood of embryo at 16th as well as at 21st day. In immunoperoxidase, T-cells (CD8+ve), pan B-cells, IgG secreting cells, IgM secreting cells and mononuclear phagocytic cells were found in all the three lymphoid organs at 16th and 21st day except IgG secreting cells, which were found only at 21st day. These studies will be helpful in better understanding the chicken immune system in embryonic and early life, for restructuring a better immunization schedule in neonatal life of chicken. ( G. K Singh ) ( Rajesh Banga) Advisor Author |
