The in vivo effects of a culture medium. II. Influence of culture medium administered prior to irradiation on hemopoietic recovery of gamma-irradiated mice.

The culture medium administered to C57Bl/6 mice 18 h and 8 h before a single irradiation (9 Gy) had a radioprotective effect and clearly influenced postirradiation changes in haemopoiesis. Haemopoiesis recovery appeared to be faster in culture medium-pretreated animals than in those irradiated without such pretreatment. By 12-15 days after irradiation, the thymus cortex appeared to be repaired, on day 21 a multiple increase in extramedullary erythropoiesis, myelopoiesis and megakaryocytopoiesis in the red pulp was found and later, on day 28, the lymphopoiesis in the white pulp of spleen was restored. The rate of haemopoiesis proliferation of predominantly myeloid cells which reached a control level on day 28 following irradiation. Consequently, the regenerative processes in blood-forming organs were accompanied by considerable reticulocytosis and complete recovery of neutrophil and platelet counts in the peripheral blood as seen on day 21. Despite a slower rate complete recovery of the total leukocyte count was reached by day 180 after irradiation.