A MECHANISM FOR VIRILIZATION OF FEMALE SPOTTED HYENAS INUTERO

Female spotted hyenas exhibit male-like genitalia and dominance over m ales. Hyena ovarian tissues incubated in vitro produced large quantiti es of the steroid hormone precursor androstenedione. The activity of a romatase, which converts androstenedione to estrogen, was one-twentiet h as great in hyena versus human placental homogenates. In comparison, the activity of 17beta-hydroxysteroid dehydrogenase, which converts a ndrostenedione to testosterone, was equal in the two homogenates. The limited aromatase activity may allow the hyena placenta to convert hig h circulating concentrations of androstenedione to testosterone, which results in virilization of the fetal external genitalia and possibly destruction of fetal ovarian follicles. Androstenedione production by residual ovarian stromal cells during reproductive life accounts for t he epigenetic transmission of virilization in female spotted hyenas.