SUMMARY
1. Assay of the potency of the recently isolated plant oestrogen, miroestrol, shows that when given subcutaneously in multiple doses it is as potent as oestradiol-17β, and orally more than three times as potent as stilboestrol in producing an increase in uterine weight in the immature female mouse.
2. In the immature female mouse given a single injection of oestrogens, the route of administration influences the magnitude, the latent period, and the duration of the responses in the reproductive tract. In general, the oestrogens act most efficiently on the uterus and vagina when they are given intraperitoneally instead of subcutaneously. It is suggested that this is because there is less chance of absorption rates and metabolism in the animal influencing the oestrogen introduced intraperitoneally.
3. The activity of miroestrol by single injection is described and compared with that of oestriol, oestradiol-17β and stilboestrol. It is at least as effective as oestradiol-17β and stilboestrol in promoting uterine and vaginal growth, and in increasing the amount of fluid which can be expressed from the uterine lumen by gentle pressing.
Altered sexual differentiation of hepatic uridine diphosphate glucuronyltransferase by neonatal hormone treatment in rats
