Tianfu Duck Spleen Growth And Development And The Study Of Cell Proliferation And Apoptosis

130 Tianfu ducks were divided into 26 groups as follows:13groups in the embryonic period (one group per day from 16 to 28 embryonic days),13 groups after hatching (0,1,2,3,4,5,8,11,14.17,20,23,32weeks).To study the morphological and histological structures, cell apoptosis and proliferation, apoptotic genes and proteins expression in the spleen during the embryonic and post embryonic development were studied by using morphological methods, immunohistochemisty, light microscopy, in sita hybridization and terminal deoxynucleotidyl transferase biotin-dUTP nick end labelling (TUNEL) techniques.Results showed that during the embryonic and post embryonic development, the morphological and histological structures of the spleen underwent obvious age-related changes. Development of embryonic spleen was divided into two stages as follows: (1) slow development period (16D～23D). (2) fast development period (23D～8W). The development of post embryonic spleen was also divided into two stages: (1), continuing development period (0～14W). (3) sustained period (14～32W).In the embryonic spleen, the apoptosis rate of lymphocytes in the white and red pulps keeped rising from 16 to 27 days. In the postembryonic spleen, the apoptosis rate of lymphocytes in the spleen nodule followed a series of changes as rising (from neonatal stage to 4 weeks and 11 to 20weeks), dropping (from 4 to 11 weeks and 20 to 32 weeks). The apoptosis rate of lymphocytes in the Periarterial lymphatic sheath (PALS) increased from neonatal stage to 32 weeks. The apoptosis rate of lymphocytes in the red pulp increased from neonatal stage to 11 weeks and decreased from 11 to 32 weeks. In the embryonic spleen, the proliferative indexes of lymphocytes in the white and red pulps rose from 16 to 27 days. In the postembryonic spleen, the proliferative indexes of lymphocytes in the spleen nodule dropped from neonatal stage to 4 weeks, maintained at a certain level from 4 to 20 weeks, and decreaseded from 20 to 32 weeks.The proliferative indexes of lymphocytes in the PALS and red pulp decreased from neonatal stage to 32 weeks. During embryonic and postembryonic spleen, the Bcl-2 positive ratios of lymphocytes paralleled reversely with the apoptosis ratios of lymphocytes (except from 19 to 23 days in the red pulp of the embryonic spleen, and from the neonatal stage to 1 week and from 11 to 20 weeks in the spleen nodule, and from 20 to 32 weeks in the red pulp of the postembryonic spleen).In the embryonic and postembryonic spleen, the Bax positive ratios of lymphocytes presented the similar change pattern to the apoptosis ratios of lymphocytes (except from 19 to 23 days in red pulp of the embryonic spleen, and from 4 to 20 weeks in the spleen nodule, and from the neonatal stage to 1 week and from 4 to 11 weeks and from 20 to 32 weeks in the red pulp of the postembryonic spleen). In the embryonic and postembryonic spleen, the ratios of Bcl-2 and Bax of lymphocytes paralleled reversely with the apoptosis ratios of lymphocytes (except from 11 to 20 weeks in the spleen nodule, and from 1 to 4 weeks in the red pulp of the postembryonic spleen)During embryonic development of the spleen, the positive ratios of Bcl-2 and BaxmRNA of lymphocytes in the white pulp and red pulp were similar to the positive ratios of Bcl-2 and Bax proteins. During post embryonic development of the spleen the positive ratios of Bcl-2 mRNA of lymphocytes in the the PALS and red pulp showed the similarly change patterns with those of the positive ratios of Bcl-2 proteins. The change patterns of the positive ratios of BaxmRNA of lymphocytes in the spleen nodule, PALS and red pulp were basically similar to those of the positive ratios of Bax proteins (except from neonatal stage to 11 weeks and from 20 to 32 weeks in the spleen nodule). Bcl-2 and BaxmRNA of lymphocytes in the spleen were different from those of their proteins in the tissue distribution, whose expression presented the regulative mechanism after transcription.Based on the results mentioned above, it showed that the morphological and histological structures, cell proliferation and apoptosis, apoptotic proteins and genes expression in the Tianfu duck spleen underwent obvious age-related changes during embryonic and post embryonic development.The cell proliferation and apoptosis supervised and controlled the proliferation and differentiation of T, B lymphocytes cooperatively, which played significant and regulatory roles in the development of the duck spleen. Bcl-2 and Bax apoptotic proteins and Bcl-2 and BaxmRNA genes modulated the apoptosis of lymphocytes in the spleen.