[The effect of 5-fluorouracil on the clonogenic hematopoietic cells (CFU-S) of embryonic and sexually mature mice].

We studied sensitivity of various types of clonogenic hemopoietic cells (CFU-S-7, CFU-S-11, and CFU-ep) on the liver of 14-days embryos and from the bone marrow and spleen of adult mice to the cytotoxic agent 5-fluorouracil (5-FU) in vitro and in vivo. We discovered that different types of CFU-S of the embryos and adult mice has similar sensitivity to 5-FU in vitro. At the same time in vivo the bone marrow CFU-S-7 display a higher sensitivity to 5-FU than CFU-S-11, thus agreeing with the published data (Hodgson and Bradley, 1979). The differences between the 5-FU effects in vitro and in vivo are related to the hemopoietic microenvironment, which modulates the cytotoxic 5-FU effect in vivo.