3d image of pregnane skeletal formula

pregnane c21 steroid parent progesterone allopregnane gonane core pregnanediones pregnanolones pregnanediols derivative pregnenes pregnadienes pregnatrienes hormone hormonal therapy replacement function action endocrine endocrinology level prohormone analogue metabolite metabolism biosynthesis mechanism biosynthetic intermediate biogenesis substrate precursor synthesis bioprecursor metabolic enzyme endogenous mother gynecology woman reproductive female sex menopausal pregnancy 3d