Abstract
The experimental analysis of the sexual cycle carried out particularly during the last fifteen years makes it possible to state the main factors regulating its mechanism. While this analysis rests largely on experiments and observations in rodents, and especially in the guinea pig, yet in principle conditions seem to be similar in all the mammals.
Two phases can be distinguished in the sexual cycle; the first phase is dominated by an ovarian factor other than the corpus luteum, in all probability by the maturing follicles the wall of which secretes a substance which causes various kinds of circulatory changes and growth processes and in addition certain psychical alterations. Proliferation, under the influence of this substance, occurs in the mammary gland, in the vagina and also in the uterine wall; this substance calls forth changes in the ovary which culminate in ovulation.
These growth processes usually cease in the vagina suddenly with the appearance of oestrus, while in the mammary gland they may continue for a short time longer.
Ovulation leads to the formation of the corpus luteum. The second phase of the sexual cycle is dominated by a substance or substances given off by the corpus luteum. This substance or these substances sensitize the uterus, making possible the production of decidua or of placentomata, or the normal predecidual proliferation and facilitating the fixation and development of the fertilized ovum; they cause growth processes in the mammary gland and prevent procestrus, estrus and ovulation; the corpus luteum on the other hand does not prevent the maturation of follicles, at least in rodents. The corpus luteurn substance is without a direct effect on vagina, tube or other connective tissue or epithelial structures of the guinea pig.
Get full access to this article
View all access options for this article.