Post fetal death development of endometrial cups in a Jenny donkey (Equus asinus)

Abstract

SummarySerial ultrasound examinations of the gravid uterus of a Jenny donkey (Equus asinus) carrying a transferred extraspecies horse (Equus caballus) conceptus between 11 and 33 days of gestation demonstrated that the embryo died before Day 33 even though the conceptus persisted in the uterus and the horse chorionic girdle invaded the maternal endometrium to form a circle of typically large horse endometrial cups in the right uterine horn. The high concentrations of horse CG secreted by these cups with its higher than usual ratio of FSH‐like to LH‐like biological activities of 1.4 compared to the 0.1 ratio of normal donkey CG hyper‐stimulated the donkey’s ovaries to develop multiple large accessory follicles and resulting secondary corpora lutea which secreted high concentrations of progestagens that persisted in her bloodstream for the next 90 days. This case illustrated that, in all likelihood, girdle invasion can happen after the death of the embryo indicating autonomy of the chorionic girdle.