ONTOGENETIC AND PHYLOGENETIC DISTRIBUTION OF HYDROXYSTEROID DEHYDROGENASES IN THE VERTEBRATE KIDNEY

Abstract

SUMMARY: The human pronephros showed no hydroxysteroid dehydrogenase activity. The human mesonephros, like piscine and amphibian mesonephroi had 16β- and 17β-hydroxysteroid dehydrogenase activity and a possible function of the human mesonephros is suggested. Metanephric kidneys had 3α-, Δ⁵-3β-, 3β-, 6β-, 16α-, 16β-, and 17β-hydroxysteroid dehydrogenases; 11β-hydroxysteroid dehydrogenase was present in all adult mammalian metanephric kidneys surveyed. 3α-Hydroxysteroid dehydrogenase was selectively present and very active in the proximal and distal convoluted tubules, particularly of the juxta-medullary glomeruli. This function is thought to be related to the excretion of 3α-ketosteroids. 11β-Hydroxysteroid dehydrogenase was confined to the collecting tubules and its possible involvement in the metabolism of cortisol, aldosterone or androgens in the kidney is noted. 17β-Hydroxysteroid dehydrogenase may be concerned in the excretion of the sex steroids; it occurs throughout the nephron. Δ⁵-3β-, 16α-, and 16β-hydroxysteroid dehydrogenases were not as active histochemically in the kidney as the 3α-, 3β-, 11β- and 17β-hydroxysteroid dehydrogenases.