[Proliferative activity of stromal cells--bone marrow precursors possessing clonogenic properties].

Proliferative activity of bone marrow clonogenic stromal precursor cells was studied by using the thymidine "suicide" method in vitro. Crude bone marrow stromal clonogenic cells failed to proliferate in vivo. But 24 hours after the explantation they entered the S-period and formed colonies of fibroblasts in monolayer cultures. 39+/-4% of these clonogenic cells were subject to thymidine "suicide". It follows that, in difference from cells-precursors in the crude bone marrow, clonogenic stromal cells were actively proliferating in monolayer cultures.