The Influence of Continuous Irradiation on the Colony-forming Activity of Mouse Bone-marrow

Abstract
Changes in the count of stem-cells in the bone-marrow of 12 week old C57B1 mice after continuous irradiation by gamma-rays at a low dose-rate are reported. The results suggest that the number of stem-cells in the bone-marrow must 1st considerably decrease and only then are the missing elements replenished. As soon as this occurs, the stem-cells count becomes dependent on the dose-rate. If this is low enough, the number of stem-cells may rapidly jump up to a normal level and then slowly decrease. The curve acquires a wavy course at the rate of 2.7 R/day.