[Aminoglutethimide, an inhibitor of aromatase from chick embryo ovary]

The gonads from 13-day-old female chick embryos were cultured in vitro on TC medium 199, and oestradiol production was measured by radioimmunoassay. In the presence of dehydroepiandrosterone as substrate, oestradiol synthesis was markedly increased, but when aminoglutethimide was also present, it was greatly reduced, depending on the concentration of the drug. This result demonstrates inhibition of the aromatizing enzyme system of the chick embryo ovary by aminoglutethimide in vitro. However, sex differentiation of the female gonads was not modified after in vivo treatment. Since it is not known whether their production is completely suppressed in vivo, the hypothesis cannot be dismissed that oestrogens play a role in ovarian differentiation.