Effect of Oestrin on Gonad Stimulating Power of the Hypophysis. ∗

Abstract

Smith and Engle 1 showed that the anterior lobe of the hypophysis of the guinea pig in oestrum is less potent in its gonad stimulating power than the hypophysis of animals in the dioestrum. Burch and Cunningham 2 reported that injection of a commercial placental extract, containing considerable amounts of oestrin, into adult, castrate, female rats tends to increase the gonad stimulating power of the pituitaries of such animals, as compared with non-injected castrate controls of approximately the same weight. The period of injection in their experiment was 6 days and the dosage employed was from

Thirty-four immature female rats varying in age from 30 to 40 days were injected with 2 R.U., 0.1 cc., per day of an oil soluble oestrous hormone prepared from the amniotic liquor of the cow.† Twenty-eight litter-mate sisters of these experimental animals were injected with 0.1 cc. of Mazola oil and used as controls. The period of injection varied from 30 to 70 days, after which the animals were sacrificed, ovaries weighed and pituitaries implanted into female rats varying in age from 20 to 30 days. Two pituitaries were implanted simultaneously into each recipient. The criterion of gonad stimulating power of the hypophyseal implants was the time necessary for the opening of the vaginas of the recipients. This method is not satisfactory unless the vaginas of the recipients being compared open 4 or more days apart. The ovaries of the oestrin injected donors weighed 40% less than the ovaries of the control litter-mate donors. The pituitaries of the oestrin injected rats opened the vaginas of the recipients from 9 to 25 days after implantation, whereas the vaginas of control recipients which received pituitaries from the control donors opened 4 to 5 days after implantation.