| Abstract: | Autoradiographic studies were performed to investigate the changes in cellular proliferation of splenic cells after sham operation and 2/3 partial hepatectomy. Material and Methods: 54 female Wistar rats were hepatectomized and 27 rats were sham operated. The life span of the animals ranged between 12 hours and 31 days. One hour before sacrificing, the animals were injected intraperitoneally with 3H-thymidine (2.5 muCi/Ig). Liver and spleen were embedded in paraffin and epoxy. In strippingfilm autoradiograms (Kodak, AR 10) and in semithinsection autoradiograms (Eastman Kodak, NTB 2) labeling indices of the hepatocytes and Kupgger cells of the regenerating liver and of the cells in the white and red pulp as well as in the marginal zone of the spleen were measured. Results and Discussion: After 2/3 partial hepactectomy there is a marked increase of proliferating. DNA synthezising basophilic blasts and basophilic and polychromatic erythroblasts in the red pulp of the spleen of rats during the first 5 to 10 days. After the fifth day the labeling index of the myelopoietic cells increases too. The curve of the percentages of radioactive labeled cells in the red pulp shows two peaks. The first can be observed after 24 hours and the second after 5 to 10 days. The percentages of labeled cells in the lymphatic mantle zone of the white pulp and in the marginal zone increase also during the first two postoperative days. The first maximum of labeled cells in all the zones of the spleen shows a close relationship to the maximum of proliferating DNA synthesizing cells in the regenerating liver. The second peak in the red pulp is possible caused by a nonspecific multifactorial stimulus such as operation stress, blood loss or inflammation during woundhealing. This proliferation enhancing effect in the spleen, especially on the erythropoietic cells, after partial hepatectomy, which produces a mild splenomegaly during the first 5 days, is more distinct than after sham operation, mechanical or thermical lesions on parenchymal organs. |
