Symposium on Reproduction, September 6-7, 1973, School of Veterinary Medicine, University of California, Davis : sponsored by American Veterinary Society for the Study of Breeding Soundness, American College of Theriogenologists, School of Veterinary Medicine, University of California, Davis.

  • Symposium on Reproduction (1973 : Davis, Calif.)
Date:
[1973?]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Symposium on Reproduction, September 6-7, 1973, School of Veterinary Medicine, University of California, Davis : sponsored by American Veterinary Society for the Study of Breeding Soundness, American College of Theriogenologists, School of Veterinary Medicine, University of California, Davis. Source: Wellcome Collection.

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    5 animals. The corpus luteim has a distinctive, connective tissue core sur¬ rounded by bands of luteal tissue. Vfe have produced experimental pro¬ longation of the corpus luteum by removing the utenas during the luteal phase of the cycle, as shown in the next slide. [Slide #15]. The next slide [Slide #16] shows a corpus luteum of nine days* dura¬ tion in the mare, and the next slide [Slide #17] shows a corpus luteum obtadned fron one of our hysterectomized mares, which is very similcur to the corpus luteum obtained from a mare with a spontaneous, prolonged cor¬ pus. [Slide #18] Progestin data taken from mares with spontaineous pro¬ longation of the corpus luteim and corrpared to those of hysterectcmized mares show little or no difference. Fran this we have concluded that pro¬ longation of the corpus luteum in the mare is due to a failure of the uterus to release a luteolytic factor during the latter part of luteal phase of the cycle, which normally causes regression of the corpus. It should be pointed out that our intact mares that have spontaneoiisly pro¬ longed corpora do recover their ability to control the corpus, as men¬ tioned, with resumption of cyclic ovarian activity following this. The mare is one of a relatively small number of animal species—cow, sow, ewe and guinea pig—in váiich the uterus appears to play a role in the regres¬ sion of the corpus luteum. Another unusual aspect of the estrous cycle of the mare concerns sexual receptivity. Vfe have observed sane mares with regular ovarian activity, including ovulation, exhibit no signs of sexual receptivity. The next slide [Slide #19] sho^ís progestin values fron a mare that has a