Study On The Development Of Lymphocytes In Chicken Peripheral Immune Organs

The peripheral immune organs are the place where immune competent cells ecize, proliferate and generate immune response including spleen, lymphoid nodes and lymphatic nodules of alimentary canals, respiratory tracts and genitourinary tracts. They originated from mesoderm and form at the advanced stage of fetus. Lymphocytes in peripheral immune organs immigrate from center immune organ. These lymphocytes can proliferate and generate immunological function stimulated by antigens. The peripheral immune organs are the important place that can generate immune response and their structure and function change alone with the immune response. So it is the barometer which reflects the health status of organism. Postnatal mammals can obtain maternal antibody through breast milk. But the quantity of maternal antibody in chickens out of crust is limited. How the chickens out of crust at early stage can be protected against pathogens, how the peripheral immune organs grow and whether its function is perfect to provide effective protection? All these have become the urgent study topics at present.In this study, chicken embryos of 9, 11, 13, 15, 18, 20 days and chickens of 1, 4, 7, 14, 21, 35, 56 days were choosed. Spleen, appendix and the conjunction of esophago and stomachus glandularis of 5 chickens in every stage are collected and made frozen sections. Then observe the development process and structural feature of peripheral immune organs in chickens of different development stage by HE staining method. The emergence, immigration, tissue allocation and proliferation of T, B lymphocytes and their subpopulation of different development stage in peripheral immune organs were studied by Immunohistochemistry combine with computer image analysis technique. The proportion, kinesis variation rule and interrelationship of T, B lymphocytes and subpopulation of different development stage in peripheral immune organs were analyzed by image analysis and data statistics software.The results of study show:1. White pulp and red pulp in parenchyma of spleen of embryo can be obviously discerned after 18 days. Periarterial lymphoid sheath and ellipsoid periarterial lymphoid sheath also can be obviously discerned in spleen of 4 days chicken. T, B lymphocytes in appendix basement of embryo emerge after 20 days. It is the initial shape of cecal tonsil. Crypt structure of conjunction of esophago and stomachus glandularis form obviously at 4 days. It is the initial shape of esophago tonsil. The germinal center firstly emerges in these three organs at 14 days. With the increase of day age, the characteristic structure peripheral immune organs gradually develop mature. Spleen achieve mature at 21 days and cecal tonsil at 35 days.2. IgM~+ and IgA~+ cells in spleen of embryo emerge at 15 days. IgG~+ cell, CD3~+ and CD8~+T lymphocytes of embryo emerge at 20 days. CD3~+, CD8~+ and IgM~+ cells in cecal tonsil of embryo emerge at 20 days. However CD4~+, IgG~+ and IgA~+ cells all emerge in 1 day age chicken out of crust. CD3~+, CD4~+, CD8~+, IgM~+ and IgG~+ cells in esophago tonsil of embryo all emerge at 20 days. However IgA~+ cells emerge in 1 day age chicken out of crust.3. The amount of T, B lymphocytes in peripheral immune organs increase follow with the increase of day age, and hold an upgrade tendency. The amount of T, B lymphocytes in spleen achieved stabilization at 21 days, and in tonsil of esophago and appendix at 35 days. CD8~+ cell is the main T lymphocyte subset in spleen, and B lymphocyte mainly is IgG~+ cell, moreover the amount of these B lymphocytes could exceed CD3~+ T lymphocyte subset after 7 days. CD8~+ cell is the main T lymphocyte subset in tonsil of appendix, and B lymphocyte is IgM~+ cell, and the amount could exceed CD3~+ T lymphocytes after 35 days. After 21 days, B lymphocytes in esophago tonsil are the main IgA~+ cells and the amount exceeds CD3~+ lymphocytes. The amount of CD4~+ lymphocytes is more than CD8+ lymphocytes.4. CD3~+,CD4~+ and CD8~+ T lymphocytes in spleen mainly distribute in periarterial lymphoid sheath. However IgM~+,IgG~+ and IgA~+ cells mainly distribute in ellipsoid periarterial lymphoid sheath and germinal center. T lymphocytes in appendix tonsil mainly distribute in middle and inferior part of mucous and the B lymphocytes mainly in middle and mucous between 4~7 days. Whereafter T, B lymphocytes equably distribute in mucous. CD4~+ cells arrange tightly and mainly occupy the central part in aggregates of T lymphocytes in esophago tonsil and CD8~+ lymphocytes mainly distribute in periphery. Meanwhile B lymphocytes encircle the periphery of aggregates of T lymphocytes. The aggregates of B lymphocytes is mainly the germinal center with lots of IgM~+,IgG~+ and IgA~+ cells. Meanwihle T lymphocytes encircle the periphery of aggregates of B lymphocytes.5. There is an intimate relationship between the development of tissue structure of peripheral immune organs and lymphcytopoiesis. The maturation of tissue structure is stimulated by the immigration of lymphocytes and the mature tissue structure provides place where lymphocytes grow mature and functionate. Tissue structure and the development of lymphocytes in peripheral immune organs achieve mature at 35 days. This also indicated the immune function of chicken peripheral immune organs achieve mature at 35days.The tests carry out a deepgoing study on development of tissue structure and lymphocytic generation of chicken peripheral immune organs. Thus investigate the immune status of chicken in embryo and at early stage out of crust. All these increase new content for molecular immunology and pathophysiology of fowl and provide necessary theory foundation for research in suitable immunization, pathogenic mechanism and prevention and cure of disease of chicken.