Early steroid metabolism by chick blastoderm in vitro

Yolk free blastoderms of chick embryo were incubated 3 or 22 hours with labeled pregnenolone, progesterone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone and estradiol-17 beta. Metabolites and unconverted substrates were found both in the incubation medium and in the cells. Enzymes responsible for identified conversions were: 17 alpha-hydroxylase, 17-20-desmolase, delta 5 3 beta- and 3 alpha-hydroxysteroid dehydrogenase, 17 beta-hydroxysteroid dehydrogenase and 5 alpha- and 5 beta-reductase. The results suggest that the steroid metabolizing enzyme activities found may reflect a more general ability of early embryonic cells.