RADIOIMMUNOASSAY OF STEROIDS PRODUCED BY CHICK-EMBRYO GONADS CULTURED IN THE PRESENCE OF SOME EXOGENOUS STEROID PRECURSORS

Gonads from white Leghorn chick embryos 15- and 18-days old were cultured in synthetic medium for 24 or 48 hr. Radioimmunoassay after ether extraction of the media and the homogenized organs allowed us to determine the amount of secreted steroids. Addition of precursors of sex hormones, such as pregnenolone, DHA, and Δ4-androstenedione to the culture media, increases significantly steroid production, but in patterns appropriate with respect to the sexual differences observed in control gonads. Our different experimental series obviously demonstrate that enzymes involved in the different steps of steroid biosynthesis remain active in our experimental in vitro system and are able to convert, even after 24 hr of culture, the sexual hormone precursors. the limiting factor of the in vitro steroid production in our experiments, seems to be the presence of precursors such as pregnenolone, DHA, or Δ4-androstenedione. © 1979.