Effect of the U-2 fraction of splenic extract from Horsfield's terrapin on the hematopoiesis of mammals

Intraperitoneal administration of a spleen extract from Testudo horsfieldi and its U-2 fraction increases the number of endogenous splenic haemopoietic colonies. The U-2 fraction administered to irradiated (4 Gy) mice increases the number of bone marrow CFUs. Bone marrow cells of exposed (4 Gy) mice preincubated in vitro with the U-2 fraction also increase the number of exogenous colonies in the recipient's spleen.