Abstract
Differences in 30-day percent survival in dd/YF male mice after a single dose of 600 R were observed after three kinds of hematopoietic stimulation, i. e., fasting and refeeding, heavy breeding and low barometric treatment. Erythropoietic activity was estimated by measuring 59Fe uptake for six hours into the femur and spleen after the stimulation. Number of colony forming cells in the bone marrow was determined by adopting the transplantation method. Mice appeared to be resistant when the hematopoietic activity is high and hematopoietic stem cells in the marrow are reduced.
