Failure of endometrial cup development in the donkey-in-horse model of equine abortion.

The research paper is about a study done on the failure of endometrial cup development in the donkey-in-horse model of equine abortion. It seeks to determine the mechanisms that cause this failure using histological and ultrastructural comparative studies.

Study Design and Objective

• The researchers carried out comparative studies on the mature preinvasive chorionic girdles of a horse, mule, donkey, and an extraspecies donkey-in-horse conceptus.
• This comparison was also extended to the young endometrial cups on the 37th day of gestation in mares carrying horse, mule, and transferred donkey-in-horse conceptuses.
• The primary objective was to o explore possible mechanisms responsible for the failure of endometrial cup development in the donkey-in-horse model of equine abortion.

Findings

• The researchers discovered that the progenitor chorionic girdle from the failing donkey-in-house pregnancy was similar in size to the normal donkey chorionic girdle.
• However, the trophoblast cells in the former were smaller and less organised and showed definite signs of degeneration and pyknosis.
• In the horse and mule pregnancies, the recently invaded, differentiated, and enlarging endometrial cup cells had penetrated deeply into the endometrial stroma and were packing tightly between the persisting endometrial glands on the 37th day.
• In contrast, only a few donkey chorionic girdle cells had initiated the invasion process in the donkey-in-horse pregnancy.
• These cells, after dislodging the horse’s luminal epithelium, did not pass through the luminal epithelium’s basement membrane. Only a limited number of these cells reached the endometrial stroma and these have already brought significant numbers of lymphocytes to the area.

Conclusion

• The study concludes that unknown factors in the horse uterus are adversely affecting all phases of the development, attachment, and invasion of donkey chorionic girdle cells.
• This leads to minimal or no endometrial cup development and no secretion of equine chorionic gonadotropin in the extraspecific donkey-in-horse pregnancy created by embryo transfer.