CELLULAR ASPECTS OF THE MAMMALIAN RADIATION SYNDROME: NUCLEATED CELL DEPLETION IN THE BONE MARROW

Abstract

Experiments were performed to test whether the depletion of nucleated cells in the bone marrow of irradiated mice follows a course predicted by the theory that reproductive inhibition alone is operative, or whether a radiation-induced acceleration of cell removal processes also makes a substantial contribution. Nucleated cell interconversions could be ignored in these experiments, and conditions were used which would minimize or eliminate effects of reversible mitotic lag. The data indicated that the rate of cell depletion is immeasurably low at 24-33 rads, becomes detectable at 48 rads, and reaches a maximum rate at about 190 rads, which is maintained without alteration, even up to doses close to 2000 rads. The behavior fails to indicate any measurable contribution by accelerated removal processes induced by the radiation. The effective half-life for the population of nucleated cells in the bone marrow of 6-week-old, Swiss female mice was calculated to be 10.8 [plus or minus] 3.4 hr.