Reproduction in mules: Embryo transfer using sterile recipients

Summary Four ovariectomised mares were used as recipients for embryo transfer. They were given 300 mg progesterone in oil intramuscularly daily for five days before transfer and were subsequently maintained on this treatment. Embryos were recovered and transferred non‐surgically seven or eight days after the donor mares had ovulated. A total of seven embryos were transferred and pregnancy was established in three of the four recipients. At the time of writing, these pregnancies have developed normally to Days 155, 92 and 82 of gestation, respectively.

Section: Introductionmentioning

confidence: 99%

Pregnancy in ovariectomised mares achieved by embryo transfer: A preliminary study

Hinrichs

Sertich

Cummings

et al. 1985

“…The results of this study highlight the amazing ability of Equidae to carry to term fully extraspecific foetuses of widely differing phenotype and karyotype. Thus, it has now been established that : (a) The domestic horse E caballus (2n = 64) will carry Eprzewalski (2n = 66), Eassinus (2n = 62) and E burchelli 2n = 44) foals ; (b) the domestic donkey E assinus (2n = 62) will carry E caballus and E burchelli foals; and (c) the interspecies hybrid mule E rnulus rnulus (2n = 63) will carry both E caballus and E assinus foals successfully (Allen 1982a;Bennett and Foster 1985;Davies, Antczak and Allen 1985). The immunological implications of the intimate association of cells of such different genotypes at the foetomaternal interface in these pregnancies are intriguing and they are discussed elsewhere Antczak, Davies, Kydd and Allen 1985).…”

Section: Discussionmentioning

confidence: 99%

Transfer of exotic equine embryos to domestic horses and donkeys

Kydd¹,

Boyle²,

Allen³

et al. 1985

Self Cite

Summary A total of 43 non‐surgical embryo recoveries performed on two Przewalski's horse mares (Equus przewalski) and two Grant's zebra mares (E burchelli) yielded 11 Przewalski and 14 zebra embryos. Surgical transfer of nine Przewalski embryos to domestic pony recipient mares resulted in seven (78 per cent) extraspecific pregnancies. Two of these recipient mares gave birth to live foals on Days 324 and 329 of gestation respectively and two are at Days 175 and 166 respectively at the time of writing; three conceptuses were resorbed at various times between Days 20 and 100. Non‐surgical transfer of two Przewalski's horse embryos and flank surgical transfer of one other Przewalski's horse embryo to domestic mares failed to establish any pregnancy. Surgical transfer of five zebra embryos to domestic pony recipients resulted in three (60 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 61 and 70 and the other two are at Days 190 and 201 respectively at the time of writing. Surgical transfer of seven zebra embryos to jenny donkeys gave two (29 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 53 and 79 and the other foal was born prematurely on Day 292 and lived for only 3 h. Non‐surgical transfer of one Day 10 zebra embryo to a jenny donkey did not result in a pregnancy. These experiments demonstrated that it is possible repeatedly to recover embryos non‐surgically from sedated wild equids and transfer them successfully to domestic horse and donkey recipients. The production of such extraspecific pregnancies by embryo transfer has considerable value as a research tool and the technique should also prove valuable in the future for maximising the reproductive potential of endangered equine species in captivity.

“…The intra-and interspecific pregnancies were established by natural mating and the horse-in-mule and donkey-in-mule pregnancies were established by embryo transfer as described by Davies, Antczak and Allen (1985). Levels of eCG in maternal serum were measured by haemagglutination inhibition assay as described by Allen (1969).…”

Section: Experimental Methodsmentioning

confidence: 99%

Immunological aspects of pregnancy in mules

Antczak

Davies

Kydd

et al. 1985

Self Cite

Summary The pregnant mare makes a range of immune responses to paternally‐inherited foetal histocompatibility antigens. Cytotoxic antibody is first detected in major histocompatibility complex (MHC)‐incompatible pregnancies by Days 50 to 70 of gestation. This follows shortly after the development of the endometrial cups and is concurrent with a striking accumulation of maternal lymphocytes and other mononuclear cells in the endometrial stroma around each cup. No such cellular infiltration occurs at the endometrium‐allantochorion border. The temporal coincidence between endometrial cup formation, cytotoxic alloantibody production and the accumulation of maternal lymphocytes suggests that these three events are interrelated. The relationships have been explored using immunogenetic markers in intraspecies horse pregnancy, by comparing immunological and endocrinological aspects of pregnancy in mares and jenny donkeys carrying normal intra‐specific and interspecific hybrid conceptuses and, finally, by examining foetomaternal interactions in sterile interspecies mules carrying pregnancies of both parental types created by embryo transfer. The working hypothesis has been that the endometrial cups are the source of immunogenic foetal histocompatibility antigen in equine pregnancy and that the cytotoxic antibody response and the lymphocyte accumulation around the cups represent humoral and cell‐mediated arms of the maternal immune response. Establishment of MHC‐compatible pregnancies demonstrated no significant effect of MHC differences between mother and foetus on serum equine chorionic gonadotrophin (eCG) levels, the duration of eCG secretion or the magnitude of the maternal leucocyte accumulation around the cups. Comparison of intraspecies horse and donkey pregnancies showed major differences between the two, including lower serum eCG levels, smaller endometrial cups with reduced leucocyte accumulation and a lower incidence of maternal sensitisation to foetal histocompatibility antigens in donkey pregnancy. Examination of interspecies mule and hinny pregnancies, on the other hand, showed a marked increase in the maternal lymphocyte reaction around the endometrial cups and a definite influence of the paternal genome of the foetus on eCG production. The successful transfer of horse and donkey embryos to female mules demonstrated that: (a) Both horse and donkey conceptuses express histocompatibility antigen in immunogenic form early in pregnancy; (b) both horse and donkey chorionic girdle cells can invade the endometrium of the mule to form endometrial cups, the eCG production rate of which is dependant upon foetal genotype; and (c) the magnitude of the lymphocyte accumulation around the endometrial cups does not correlate with known genetic differences between mother and foetus.