Interrenal function during amphibian metamorphosis: in vitro biosynthesis of radioactive corticosteroids from (4(14)C)-progesterone by interrenal in Xenopus laevis tadpoles.

Whole kidneys of Xenopus laevis tadpoles (containing interrenal cells) or the outer postero-dorsal part of adult kidney (containing a few or no interrenal cells) were incubated with (4(14)C)-progesterone. Methylene chloride extractable radioactivity of tissue homogenates in their incubation medium were purified by sequential paper chromatography and identification of some isolated fractions was attempted. A significant conversion of progesterone was only observed when interrenals were present in incubation; however, possible steroidogenic activity of the other tissue types present in the kidney cannot be ignored. At all the developmental stages of tadpoles (from stage 45 to stage 66) and in juveniles, the same steroids were isolated. Hence the metabolic pathways for corticosteroidogenesis in Xenopus laevis remained unchanged during metamorphosis and several weeks after the end of this process. Aldosterone was identified. Corticosterone and 11-dehydrocorticosterone were also synthesized but not completely purified. Their yields were always larger than those of aldosterone. Cortisol was never detected.