External Evidence of Hormone Action Following Injection of Urine of Pregnant Women into Rabbits and Guinea Pigs

Abstract

These experiments were undertaken in an effort to find a manifestation of the presence of the pregnancy hormones that would not involve operating on an animal.

The speed and accuracy of the Friedman test pointed to the rabbit as the animal of choice. Vaginal smears were made on 6 female rabbits for a period of about a month. However, it was noted that there was no regularity in the appearance of the various types of cells, and that the injection of the urine of a pregnant woman, while producing the characteristic ovarian changes, did not affect the vaginal smears. This confirms the work of Kunde and Proud. 1

Part of the explanation may lie in the anatomy of the rabbit. A dissection revealed that the urethra opens into the vagina at some distance from the vulva. Bladder epithelial cells may be washed into the vagina with the urine; a platinum loop will pass as easily into the bladder as further into the vagina. Smears made from vaginal washings showed very little difference in composition from those made with a loop.

The guinea pig was then investigated. This animal possesses a membrane which seals off the vagina except during oestrus and parturition. 2 A series of immature guinea pigs was injected with the urine of a pregnant woman near term. One received 1 cc. intraperitoneally twice a day, the other 2 received subcutaneous injections of the same amount once a day and 3 times a day respectively. In all 3 of these animals it was noted on the third day of the experiment that the vaginal membrane had ruptured spontaneously. The smears of the 2 animals receiving the larger doses showed typical proestrus cells.