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Theriogenology1987; 27(4); 655-663; doi: 10.1016/0093-691x(87)90059-8

Role of progesterone in mobility, fixation, orientation, and survival of the equine embryonic vesicle.

Abstract: Luteal progesterone was removed by an injection of prostaglandin F2alpha or bilateral ovariectomy on Day 12 of pregnancy in pony mares. The embryonic vesicle remained mobile in the uterus until loss occurred on Days 13, 13, 15, or 19 in four prostaglandin-treated mares and Days 15, 17, 19, or 26 in four ovariectomized mares. Exogenous progesterone given daily, starting on Day 12, maintained pregnancy until Day 40 in five of five prostaglandin-treated and three of four ovariectomized mares. During two-hour mobility trials on Day 14, embryonic vesicles in mares without luteal or exogenous progesterone (n=9) moved to a different uterine segment less frequently (mean number of location changes per two-hour trial: 7.2+/-1.0 vs 10.4+/-1.1, P<0.05) and were observed more often in the uterine body (14.9+/-2.9 vs 8.9+/-1.3, P<0.10) compared to vesicles in mares with a progesterone influence (n=15). Of mares that still had a vesicle present on Day 18, fixation occurred by Day 17 in all (12/12) mares under the influence of luteal or exogenous progesterone but failed to occur in the three mares that were not under progesterone influence. Progesterone replacement was started on Day 16 in three mares that received prostaglandin F2alpha on Day 12 and still had a vesicle on Day 16. The vesicle was maintained and continued to develop in all three mares, indicating that the vesicles were viable four days after PGF2alpha treatment. However, fixation tended to be delayed (P<0.15) and orientation of the embryo proper was altered (P<0.005) compared to mares that were continuously under the influence of progesterone. The results demonstrated the importance of luteal progesterone to mobility, fixation, orientation, and survival of the embryonic vesicle.
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Publication Date: 1987-04-01 PubMed ID: 16726270DOI: 10.1016/0093-691x(87)90059-8Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research analyses the impact of the hormone progesterone on various aspects of early horse pregnancy, specifically its role in the mobility, fixation, orientation, and survival of the embryonic vesicle. The study observed that removal of this hormone led to loss of the embryo whereas replacement or provision of progesterone helped maintain pregnancy.

Study Design

  • The research involved pony mares and their pregnancies. Progesterone, which is naturally produced in the mare’s body during pregnancy, was artificially removed on Day 12 of pregnancy either by an injection of prostaglandin F2alpha or surgical removal of both ovaries.
  • The embryo’s location and development were then observed over subsequent days, with comparisons drawn between those mares that were left without progesterone and those given exogenous (external) progesterone supplements.

Findings

  • The embryos of mares without progesterone remained mobile but were lost between Days 13 and 19 for prostaglandin-treated mares or Days 15 to 26 for ovariectomized mares.
  • When mares were given daily progesterone supplements starting from Day 12, pregnancies were sustained until Day 40 in all but one case.
  • Embryonic vesicles in mares without progesterone moved less and were more often found in the uterus’ body compared to those in mares with progesterone.
  • All mares with progesterone saw their embryos get fixed by Day 17, whereas fixation did not occur in the three mares without progesterone.
  • Starting progesterone replacement on Day 16 in mares that received prostaglandin F2alpha on Day 12 helped maintain the vesicle and its development, although the fixation tended to be delayed and the embryo’s orientation altered compared to those under continuous progesterone influence.

Conclusion

  • Overall, the study found that luteal progesterone plays a vital role in different stages of a mare’s embryonic development, affecting mobility, fixation, orientation, and survival of the embryonic vesicle.

Cite This Article

APA
Kastelic JP, Adams GP, Ginther OJ. (1987). Role of progesterone in mobility, fixation, orientation, and survival of the equine embryonic vesicle. Theriogenology, 27(4), 655-663. https://doi.org/10.1016/0093-691x(87)90059-8

Publication

Theriogenology
ISSN: 0093-691X
NlmUniqueID: 0421510
Country: United States
Language: English
Volume: 27
Issue: 4
Pages: 655-663

Researcher Affiliations

Kastelic, J P
  • Department of Veterinary Science, University of Wisconsin, Madison, WI 53706, USA.
Adams, G P
    Ginther, O J

      Citations

      This article has been cited 3 times.
      1. Lufkin H, Flores D, Raider Z, Madhavan M, Dawson M, Coronel A, Sharma D, Arora R. Pre-implantation mouse embryo movement under hormonally altered conditions. Mol Hum Reprod 2023 Jan 31;29(2).
        doi: 10.1093/molehr/gaac043pubmed: 36579867google scholar: lookup
      2. Aurich C, Budik S. Early pregnancy in the horse revisited - does exception prove the rule?. J Anim Sci Biotechnol 2015;6:50.
        doi: 10.1186/s40104-015-0048-6pubmed: 26635959google scholar: lookup
      3. Siemieniuch-Tartanus M. The early pregnancy in mares - What do we still not know?. Vet Anim Sci 2025 Jun;28:100441.
        doi: 10.1016/j.vas.2025.100441pubmed: 40129505google scholar: lookup
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