Stimulatory effect of preirradiation of haemopoietic stroma with small doses on the content of haemopoeitic stem cells in the in vivo bone marrow and in a long-term culture

Preiiradiation of mouse recipients with a dose of 1 -2 Gy 24 and 48 h before lethal irradiation (8 Gy) made CFUs content of femur increase upon transplantation of bone marrow from exposed and intact donors. The same was with the long-term bone marrow culture: preirradiation of a stromal sublayer increased the number of CFUs in the transplanted bone marrow preirradiated with 6 Gy radiation. Retransplantation of bone marrow to irradiated donors after 5 day cultivation, a sublayer being activated, increased the number of CFUs in the femur in comparison with donors which were injected with the bone marrow fron the culture without activation of the sublayer by low-level radiation