Further Observations on the Pregnancy-Response of the Uterus of the Cat.

Abstract

We have previously found 1 that injections of corpus-luteum extract into non-pregnant cats even after ovariectomy change the response of the uteri so that the latter, like uteri of pregnant animals, contract when the hypogastric nerves are stimulated. If such animals are untreated or receive injections of extracts containing only oestrin, their uteri always relax in response to hypogastric nerve-stimulation, thus behaving like non-pregnant uteri.

In a new series of experiments we have injected into cats and kittens sterile urine of pregnant women. The amount injected daily was approximately 10 cc.; the period of injection was about 10 to 14 days prior to a crucial experiment in which we recorded the movements of the uterus in situ. Such urine contains oestrin as well as another substance causing precocious sexual maturity with corpusluteum formation and thought by some to originate in the pars anterior of the pituitary body.

Injected into ovariectomized cats, pregnancy-urine caused no change in uterine-response. When such injections were made into unoperated non-pregnant cats or kittens we always observed a marked follicular development, frequently with corpus-luteum formation. Only in animals the ovaries of which contained corpora lutea, did the uteri exhibit a pregnancy-response. This fact we believe constitutes further evidence that the pregnancy-response of the uterus of the cat depends at least in part on a substance elaborated by the corpus luteum.