PLACENTAL STEROID-HORMONE SYNTHESIS - UNIQUE FEATURES AND UNANSWERED QUESTIONS

Despite the amazing diversity of placental architecture across species , a number of common elements can be found, including the ability of a ll placentae to synthesize and metabolize steroid hormones; the assign ment of steroidogenic activities to specific trophoblast phenotypes; t he use of novel mechanisms to control expression of steroidogenic enzy me genes, which differ from those employed in the adrenal cortex and g onads; and interactions with the maternal and fetal compartments encom passing supply of steroid hormone precursors as well as regulatory inf luences of maternal ovarian and pituitary hormones and fetal adrenal c ortical steroids.