Compensatory Reactions in Intestinal Crypt Cells after 300 Roentgens of Cobalt-60 Gamma Irradiation

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Abstract
A single 300-R whole-body 60Co y-ray dose markedly changes the proliferative cells in the mouse duodenal crypts. Cells in all phases of the generation cycle were affected as follows: most cells in mitosis completed division, but the process was prolonged; cells in G2 were blocked in G2 for approximately 4 1/4 hr. and then experienced difficulty with mitosis; cells in S continued DNA synthesis, but at a reduced rate (however, after synthesis was completed they appeared to move through G2 and divide); and movement of G1 cells to S was retarded. During the recovery phase, when killed and less-damaged cells were being replaced, the repopulation of the crypts and the return to the normal steady-state relationship which exists between the proliferative and non-proliferative cells of the intestinal epithelium were hastened by 2 compensatory mechanisms: an acceleration of the generation cycle and an increase in the number of cells in the proliferative compartment.