[Effect of immobilization of mice with different radiosensitivities and shielding of part of the bone marrow on survival and spleen colony formation following irradiation].

Experiments on linear F1 (CBA x C57BL) mice resistant to irradiation and random-bred white mice which are more sensitive to irradiation were made to study the relationship of the survival rate of the animals and spleen colony formation to the magnitude of x-ray doses during immobilization and shielding of the crus--factors which increase the resistance. It was shown that low colony formation typical for linear mice remained at a low level during the resistance-increasing immobilization, while in the course of shielding it increased in accordance with the animals' survival rate. In random-bred mice, the survival rate and colony formation were in good agreement in all the cases. The conclusion is made that colony formation cannot be regarded as an adequate criterion for the survival rate.