Variations in aldosterone and corticosterone plasma levels during metamorphosis in Xenopus laevis tadpoles

Aldosterone and corticosterone plasma levels have been determined by radioimmunoassay at various stages (St) of metamorphosis in Xenopus laevis tadpoles. The aldo level first showed a significant peak at the beginning of the climax (St 58), and again at the middle of the climax (St 61-62); B level increased slightly but significantly at St 59, then showed an important peak at St 62-63. The high levels of these hormones at these stages seem to be associated with the concomitant surge of interrenal synthesis. At this stage, the plasma level of thyroid hormones is maximal, and the main morphological changes occur. Therefore, corticosteroids and thyroid hormones could have synergistic effects on morphogenesis. A relationship is assumed between the surge of corticosterone at the middle of the climax, and the glucocorticoid function of this hormone. Aldosterone could play a part in the differentiation of adult skin.