[Differential radiation susceptibility of endogenous precursor cells forming "early" and "late" hematopoietic foci in the spleen of mice].
No colonies were found in the spleen at "early" times (7-8 days) after irradiation of mice with doses of 8-9 Gy, while at "later" times (after 15 days) a confluent growth of the colonies was observed. The endogenous splenic foci of haemopoiesis of the "late" type were characterized by the preferable growth of granulocytic colonies.