CHANGES IN THE WEIGHT AND WATER CONTENT OF THE UTERUS OF THE NORMAL ADULT RAT

Abstract

Detns. on the wt. and water content of the uteri of adult rats during the estrous cycle and during pseudopregnancy showed that the uteri reach a maximum size at proestrus and then regressed to a minimum on the first day of diestrus. Their water content rose to a maximum before proestrus and then fell abruptly with the first appearance of cornified cells in the vaginal smear. Uteri of pseudopregnant animals followed the same course for the first 3 days, showed an increase in wt. and water content on the 5th day, and then regress below the diestrus level. The uteri of animals in various stages of the cycle, given a single inj. of 2.0 [gamma] estradiol 6 hrs. before death, responded by a marked increase in tissue water during diestrus and preestrus. During proestrus and estrus this reaction was strongly inhibited. Evidence showed that this inhibition was due to an ovarian secretion having the properties of a corpus luteum hormone. Estrogen probably acted unopposed during a brief period before proestrus and largely ceased to be produced prior to vaginal cornification. Corpus luteum hormone acted upon the uterus during proestrus and estrus; it was released from ovarian follicles during their preovulatory swelling and ceased to be produced at or shortly after ovulation.