PHYSIOLOGY OF THE CORPUS LUTEUM

Abstract

Ovulation in a series of rabbits was induced by mating and 14 to 20 hrs. later, when the ova were in the Fallopian tube, experimental modification of the ovaries was performed by surgical intervention. In one group, both ovaries were removed; in another, the ovaries were incised and partially removed, leaving one or more corpora lutea. In the third group all the corpora lutea were excised, leaving portions of the ovary in situ. The animals were autopsied 4-8 days later to determine the fate of the fertilized ova and the presence or absence of progesta-tional proliferation of the endometrium. The experiments confirm the existence of progestational proliferation of the rabbit''s uterus during the earliest days of pregnancy, and support the discovery of Bouin and Ancel that this effect is dependent on the corpora lutea. They also confirm Fraenkel''s view that the corpora lutea are necessary to implantation of the embryos; and they suggest that normal implantation depends upon the progestational proliferation of the endometrium. They also indicate that the uterine proliferation is necessary not only for implantation, but for the nutrition or protection of the free blastocysts during the period of 3-4 days between arrival in the uterus and implantation. Finally, these results point strongly to the existence of a special action of the corpus luteum upon the endometrium, bringing about progestational proliferation.