Abstract
Summary The compensatory renal hyper-plasia that normally follows unilateral ne-phrectomy is abolished by bilateral adrenal-ectomy if rats are maintained on fresh drinking water, but is restored when saline drinking water is provided or if such animals are injected with desoxycorticosterone. The adrenals are also important for the heightened proliferation caused by unilateral hydrone-phrosis. These experiments suggest that the role of the adrenal cortex in renal hyperplasia may be to secrete mineralocorticoids, which promote the retention of sodium and thereby stimulate cell division in the kidneys.