Rhythmic variations in the vascularity of the uterus of the guinea pig during the estrous cycle

Abstract

T HE vascularity of the uterus of the guinea pig undergoes cyclic variations that make it appear to blush and blanch. Both the speed and the extent of these vascular changes are affected by the time of day and the stage of the estrous cycle. We have been unable to find similar vascular changes in any other tissue, either in situ or in transplants to the anterior chamber of the eye, of pancreas, islands of Dangerhans, vas deferens, heart muscle, or liver. These vascular changes were studied by three methods: First, by opening the abdominal cavity and studying the gross and microscopic changes in the uterus in situ; second, by transplanting a piece of endometrium to the anterior chamber of the eye by the method described by Dr. S. S. Schochet in Szcrgery, Gynecology and Obstetrics, in 1920, and third, by inserting a small tube through the vagina and half way up the horn of the uterus and observing the changes in the endometrium through that tube. By the first method, namely, opening the abdominal cavity of an a.nesthetized guinea pig, we found that the whole uterus was red most of the time. About every minute a light area appeared at the upper end of the horns and spread down them toward the cervix. The whole uterus was white for ten or fifteen seconds and then t,he region above the cervix became red and the red color spread up the horns of the titerus. These changes occurred about once a minute during the diestrum and much more slowly during estrus. We were unable to observe them in immature animals. It is possible to make much more d.etailed observations on endometrium transplanted to the anterior chamber of the eye. Figs. 1 and 2 represent the two phases of an endometrial transplant in the anterior chamber of the eye of a guinea Pk. The former represents the condition when the transplant is white; the latter the condition fifteen seconds later when it is red. By comparison with a Tallqvist hemoglobinometer we found that the two colors were comparable with the colors indicated by 0 and 50 per cent hemoglobin respectively. We made twenty-minute records every two hours for three complete estrous cycles of sixteen days each. Two o-f the records were made on -*Read at a meetin,of the Chicago Gynecological Society, April 20. 1928. This research was conducted under a grant from the Douglas Smith Foundation for Medical Research of the University of Chicago.