Extraspecific donkey-in-horse pregnancy as a model of early fetal death
Allen, W.R.; Kydd, J.H.; Boyle, M.S.; Antczak, D.F.
Journal of Reproduction and Fertility. Supplement 35: 197-209
1987
ISSN/ISBN: 0449-3087 PMID: 3479576 Document Number: 294722
In a review of the literature it is shown that endometrial cups do not develop in this type of extraspecific pregnancy, and 80% of ass foetuses are aborted between days 80 and 100 of gestation in conjunction with abnormal implantation and an intense accumulation of leukocytes in the endometrium of the surrogate mare. Treatment of mares carrying ass conceptuses with progestogen (allyl trenbolone) or purified horse chorionic gonadotropin does not prevent abortion. However, passive immunization with serum from mares carrying intraspecific horse foetuses, or active immunization with ass lymphocytes, causes a marked increase in foetal survival rate and the birth of live foals. Furthermore, both cytotoxic (rejection type) and immunoprotective maternal immune responses to the xenogeneic ass foetus can be recalled in mares carrying repeated donkey-in-horse pregnancies. It is suggested that the endometrial cup reaction in normal equine pregnancy provides a vital and temporally important antigenic stimulus which results in the mare mounting an immunoprotective response towards her allogeneic foetus in utero.