The effect of extirpation of the uterus on the life and function of the corpus luteum in the guinea pig

It is usually assumed that extirpation of the uterus is without any noticeable effect on the ovaries, outside perhaps of cystic degenerative changes which have sometimes been observed to follow this operation and which evidently are due to interference with the blood supply of the ovary following injury of the uterine vessels.

Experiments in the guinea pig have however convinced us that a complete or almost complete extirpation of the uterus may be followed by a very characteristic effect, namely a long continued preservation and function of the corpus luteum. Instead of beginning to degenerate fourteen or fifteen days after ovulation, the corpus luteum may remain well preserved and even show attempts at mitotic proliferation for sixty days, or perhaps even as late as eighty days after the last heat. We have not yet determined the limit of preservation of the corpus luteum under these conditions. The cyclic corpus luteum thus equals or perhaps surpasses in vitality the corpus luteum of pregnancy which latter has in the guinea pig a duration of about sixty-five days.

In order to demonstrate this effect we extirpated the uterus a few days after ovulation. The corpus luteum which develops as a result of ovulation remains preserved for a long time following this operation. If we extirpate the uterus in very young guinea pigs at a time when an ovulation has not yet occurred, the first ovulation takes place, notwithstanding the extirpation of the uterus. In various experiments we observed this ovulation to occur as early as nine days and as late as twenty-nine days following the operation. The corpus luteum which thus originates remains then preserved for a long period of time and mitotic figures may often be seen in the lutein cells. In ovaries of these young animals, which ovulated for the first time following hysterectomy, there is usually no remnant of retrogressing corpora lutea representing former ovulations visible. In one case, however, we found such a body side by side with a well preserved corpus luteum. This was probably due to the fact that one of the corpora lutea formed during an ovulation may retrogress earlier than the others.