Abstract
SUMMARY: Interaction in the immature mouse of potent oestrogens with the weak utero-vaginotrophic (UV) compounds, coumestrol, genistein, dimethyl-stilboestrol, norethisterone acetate and megestrol acetate though sometimes additive at very low doses appeared to be essentially antagonistic at higher doses. In particular, the weak oestrogens coumestrol and genistein, found in certain plants, markedly inhibited the UV action of potent oestrogens, e.g. oestradiol-17β, oestrone and diethylstilboestrol and this effect may account in part for the anti-oestrogenic activity of extracts of these plants. Some differences in the ability of different oestrogens to promote uterine growth relative to vaginal growth were observed.