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Factors influencing placental and fetal development in the mare: important considerations for the selection of embryo recipients

Published online by Cambridge University Press:  27 February 2018

S Wilsher  and
W R Allen
S Wilsher
Affiliation:
University of Cambridge, Department of Clinical Veterinary Medicine Equine Fertility Unit, Mertoun Paddocks Newmarket, Suffolk CB8 9BH, UK
W R Allen
Affiliation:
University of Cambridge, Department of Clinical Veterinary Medicine Equine Fertility Unit, Mertoun Paddocks Newmarket, Suffolk CB8 9BH, UK
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Extract

In mammals the placenta is the vehicle for nutritional and gaseous exchange between the maternal and fetal circulations during pregnancy. The allantochorionic placenta of equids is classified as non–deciduate, non–invasive, epitheliochorial and diffuse and, as such, equine placentation demands fetomaternal interdigitation over the entire endometrial surface to optimise fetal development in utero. Any shortcomings are reflected by slower growth and delayed maturation of the fetus.

This requirement for an unabbreviated area of placental attachment is emphasised by the inability of mares to carry twin conceptuses to term due to simple competition between the two placentae for the limited area of endometrium which results in progressive starvation of one or both fetuses (Jeffcott and Whitwell, 1973). In addition, age–related chronic degenerative changes in the mare's endometrium (endometrosis) may compromise the uterine environment during pregnancy and Bracher et al. (1996) showed a close relationship between the health of the endometrium, the normality of structure and the density of the microcotyledons on the surface of the allantochorion, and fetal weight.

Type
Research Article
Information
BSAP Occasional Publication , Volume 32: Emerging Equine Science , 2004 , pp. 87 - 89
Copyright
Copyright © British Society of Animal Production 2014

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References

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