Cell Proliferation in Compensatory Renal Growth1

SUMMARY Rats with one kidney removed showed a progressive increase in weight of the remaining kidney over a six‐week period. Autoradiographic and radiochemical studies with 3 H‐thymidine indicated that the increase in new kidney cell formation was maximal forty‐eight to seventy‐two hours after unilateral nephrectomy. This early response was chiefly due to the production of new cells by the renal cortical tubules. Normal rates of tubule cell turnover were achieved two weeks after operation. The glomerular tufts contained fewer new cells and their peak production was delayed to the one‐week period with a slow decline thereafter. Rats forty‐eight hours after unilateral nephrectomy were chosen as a model to study the effect of various substances on the magnitude of new cell formation. The number of DN A‐synthesising cells in the stimulated kidney was reduced by treatment with hydrocortisone, ACTH, 9,10‐dimethyl‐1,2‐benzanthracene, and 1,2‐benzanthracene; the numbers were increased by the administration of deoxycorticosterone and aldosterone.