The effects of an advanced uterine environment on embryonic survival in the mare.
Abstract: During embryo transfer (ET) the equine embryo can tolerate a wide degree of negative asynchrony but positive asynchrony of >2 days usually results in embryonic death. There is still confusion over whether this is due to the inability of the embryo to induce luteostasis or to an inappropriate uterine environment. Objective: To assess embryo survival and development in an advanced uterine environment. Objective: Embryo-uterine asynchrony, not the embryo's inability to induce luteostasis, is responsible for embryonic death in recipient mares with a >2 days chronologically advanced uterus. Methods: Experiment 1: Thirteen Day 7 embryos were transferred to the uteri of recipient mares with luteal prolongation, occasioned by manual crushing of their own conceptus, such that donor-recipient asynchrony was between +13 and +49 days. Experiment 2: Day 7 embryos were transferred to recipient mares carrying their own conceptus at Days 18 (n = 2), 15 (n = 2), 14 (n = 4), 12 (n = 4) or 11 (n = 4) of gestation. In addition, Day 8 embryos were transferred to 4 pregnant recipient mares on Day 11 of gestation. Results: No pregnancies resulted following transfer of Day 7 embryos to recipients in prolonged dioestrus with asynchronies between +13 and +49 days. However, the use of early pregnant mares as recipients resulted in 5/20 (25%) twin pregnancies, 4 of which came from the transfer of a Day 8 embryo to a Day 11 recipient. All transferred embryos showed retarded growth, with death occurring in 4/5 (80%). Conclusions: The results emphasise the importance of an appropriate uterine environment for embryo growth and the inability of equine embryos to survive transfer to a uterus >2 days advanced even when luteostasis is achieved. It is possible that in normal, non-ET equine pregnancy, embryo-uterine asynchrony may account for some cases of embryonic death.
© 2011 EVJ Ltd.
Publication Date: 2011-09-25 PubMed ID: 21950418DOI: 10.1111/j.2042-3306.2011.00473.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article investigates the importance of the uterine environment on the survival of equine embryos during embryo transfer (ET). More specifically, it tests the hypothesis that embryos transferred to a significantly advanced uterine environment (greater than 2 days) are likely to fail in development and result in embryonic death, despite established luteostasis.
Research Objectives
- The study primarily aims to assess survival and development rates of equine embryos in advanced uterine environments.
- It seeks to establish whether embryo-uterine asynchrony causes embryonic death in recipient mares with a uterus chronologically advanced by more than 2 days.
Methods
- The study comprises two experiments. In the first, thirteen Day 7 embryos were implanted into recipient mares’ uterus, which was artificially advanced using manual crushing of their existing conceptus to create a donor-recipient asynchrony ranging from +13 to +49 days.
- In the second experiment, Day 7 embryos were implanted into recipient mares already carrying their own conceptus from Days 11 to 18 of gestation. Day 8 embryos were also transferred to four pregnant mares on Day 11 of their gestation.
Results
- None of the Day 7 embryos transferred to recipient mares with asynchronies between +13 and +49 days developed into pregnancies.
- However, out of the 20 embryos implanted into early pregnant recipients, five (25%) resulted in twin pregnancies, four of which were conceived by a Day 8 embryo in a Day 11 recipient.
- All transferred embryos showed slowed growth and four out of five (or 80%) ended up dying.
Conclusions
- The study confirms the hypothesis that the uterine environment plays a crucial role in the growth and survival of embryos during ET procedures.
- As predicted, equine embryos could not survive when transferred to a uterus more than 2 days advanced, even if luteostasis was achieved.
- The author hypothesises that embryo-uterine asynchrony may account for some incidents of embryonic death in normal, non-ET horse pregnancies.
Cite This Article
APA
Wilsher S, Lefranc AC, Allen WR.
(2011).
The effects of an advanced uterine environment on embryonic survival in the mare.
Equine Vet J, 44(4), 432-439.
https://doi.org/10.1111/j.2042-3306.2011.00473.x Publication
Researcher Affiliations
- The Paul Mellon Laboratory of Equine Reproduction, Suffolk, UK. sandrawilsher@hotmail.co.uk
MeSH Terms
- Animals
- Cleavage Stage, Ovum / cytology
- Cleavage Stage, Ovum / physiology
- Cleavage Stage, Ovum / transplantation
- Diestrus
- Embryo Transfer / veterinary
- Embryo, Mammalian
- Embryonic Development
- Estrus Synchronization
- Female
- Horses / embryology
- Pregnancy
- Tissue Donors
- Transplantation
- Uterus / physiology
Citations
This article has been cited 2 times.- Rickard JP, Ryan G, Hall E, de Graaf SP, Hermes R. Using transrectal ultrasound to examine the effect of exogenous progesterone on early embryonic loss in sheep. PLoS One 2017;12(8):e0183659.
- Angel MA, Gil MA, Cuello C, Sanchez-Osorio J, Gomis J, Parrilla I, Vila J, Colina I, Diaz M, Reixach J, Vazquez JL, Vazquez JM, Roca J, Martinez EA. An earlier uterine environment favors the in vivo development of fresh pig morulae and blastocysts transferred by a nonsurgical deep-uterine method. J Reprod Dev 2014;60(5):371-6.
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