Abstract
In our preceding paper we have shown the incapacity of the hormone found in the urine of pregnant women (Prolan) to affect sexual development and function in hypophysectomized animals. It is now well established that Prolan is also for some reason limited in its effect on the gonad development which can be produced within 100 hours in immature normal animals, as measured in terms of ovary weight.
We can, for example, state that no matter how frequently or how much Prolan is administered the average weight of the ovaries produced in 26-day-old rats at the close of 4 days of treatment is about 60-70 mg. and the maximum in several hundred of our experiments was 102 mg. We, and other investigators, have pointed out that in contrast with this the implantation of anterior hypophyseal tissue is very markedly more effective in the ovary weights produced in young rat hosts, and we have shown that increasing “doses” of the implants also give increasing weights of the young ovaries.
As will be detailed in another communication, similar very marked effects on the immature gonads can now be secured by certain fractions out of extracts of anterior hypophyseal tissue. Here also, in contrast to Prolan, increasing doses give increasing effects on the youthful gonads. With such preparations, we have, for instance, in 100 hours produced ovaries weighing 190 mg.
We searched for a point of view which would harmonize these 3 experiences. That Prolan is totally ineffective in hypophysectomized animals and that it is only partially effective in young animals when compared with cases to which actual hypophyseal substances were administered seemed to us best explained by regarding Prolan only as an activator to a substance in the hypophysis itself which we may call a pro-hormone, a substance totally absent, of course, in hypophysectomized animals and small in amount in very young normal animals.
Get full access to this article
View all access options for this article.