[Steroidogenic function of the intra-arterial trophoblast in the rat. Ultrastructural, histoenzymologic and biochemical data].

The ultrastructural study of the intra-arterial trophoblast has revealed in the pregnant Rat a steroidogenic activity which has been confirmed by histoenzymologic observations (presence of delta 5-3 beta-HSDH and 17 beta-HSDH). At the 15th day postcoitum an in vitro investigation upon the metabolism of steroid hormone precursors suggests that the steroids (oestrogens, progestogens and androgens) secreted by the intra-arterial trophoblast have a local action upon the wall of the uterine placental arteries and are actively concerned with an important part upon the utero-placental hemodynamic as a whole.