Abstract
In former investigations I have described cyclic changes in the ovaries of the guinea pig which depend largely upon injurious influences exerted upon the ovaries in the period directly preceding ovulation. Inasmuch as ovulation depends upon degenerative changes having previously taken place in the corpora lutea, the cyclic changes in the life of the follicles are correlated with the cyclic changes in the corpus luteum. It was our aim to determine whether the same ovarian cycle existed in all mammalian ovaries; we examined for this purpose ovaries of the rabbit and of the ferret at various periods of sexual activity.
Summarizing our observations we may state that neither in the rabbit nor in the ferret do cyclic changes in the follicular apparatus of the ovaries, comparable to those of the guinea pig, occur. In the period immediately preceding or following ovulation no marked degeneration of the follicles takes place. If any follicles degenerate at all (in consequence of the circulatory changes in the ovaries during this period?), such a degeneration can only affect a few large follicles, while in the guinea pig a sudden degeneration of all the follicles, with the exception of the smallest ones, takes place during this period. The other changes subsequent to this sudden disintegration of follicles in the guinea pig are likewise absent in the rabbit and ferret.
The ovaries of the guinea pig also differ in other respects from those of the rabbit and ferret:
1. In the guinea pig a so-called “interstitial gland” is absent, while it is present in the ovaries of the rabbit and ferret.
2. In the guinea pig during heat a spontaneous ovulation usually takes place. This ovulation in no way depends upon a preceding copulation; while in the rabbit and, as far as we could determine, also in the ferret, heat as such is not sufficient, but a copulation needs to take place in order to insure ovulation.
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