The role of the fetal gonads and placenta in steroid production, maintenance of pregnancy and parturition in the mare.
Abstract: The effects of fetal gonadectomy on steroid production and the maintenance of pregnancy in the mare were studied. Removal of the fetal gonads resulted in an immediate fall in maternal plasma concentrations of conjugated and unconjugated oestrogens whereas progestagen levels remained unchanged. Hormone profiles in mares carrying sham-operated fetuses remained similar to those in unoperated control mares. Plasma levels of 13,14-dihydro-15-oxo-PGF-2 alpha (PGFM) were much lower, and uterine contractions weaker, during labour in mares carrying gonadectomized foals than in control mares. Pregnancy was maintained until parturition at term in the mares carrying gonadectomized fetuses. However, 3 of the 4 gonadectomized foals were dysmature and died during or soon after birth. The biosynthetic pathways involved in the production of oestrogens by the feto-placental unit and the possible role of oestrogens in fetal development in the pregnant mare are discussed.
Publication Date: 1979-01-01 PubMed ID: 289829
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- 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.
This article explores the impact of removing the fetal gonads on steroid hormone production and the progression of pregnancy in horses. Results indicate that the removal of these reproductive organs caused a drop in maternal estrogen levels, but didn’t affect progestagen levels, the hormone necessary for maintaining pregnancy. Despite this, the pregnant horses carried the fetus to full term.
Objective of the study
- This study aimed to determine the role of fetal gonads in strengthening pregnancy by examining the differences in hormone levels and pregnancy outcomes in mares with gonadectomized foetuses.
Methodology
- The researchers removed the fetal gonads in some mares and compared changes in hormone concentration and pregnancy progression to normal mares and those with sham-operated fetuses.
Finding 1: Impact on Steroid Production
- The removal of fetal gonads led to a notable decrease in both conjugated and unconjugated estrogens in the maternal plasma. However, it showed no effect on progestagen levels, another important hormone for pregnancy.
Finding 2: Impact on Labour
- Mares with gonadectomized foals had much lower levels of the hormone 13,14-dihydro-15-oxo-PGF-2 alpha (PGFM) during labour, leading to weaker uterine contractions than those in control mares. This hormone is associated with labour contractions.
Finding 3: Impact on Pregnancy
- Despite the hormonal changes due to gonadectomy, pregnancy in the mares was maintained until parturition, which suggests that estrogen produced by the fetal gonads might not be the only factor involved in maintaining pregnancy.
- On the downside, 3 out of the 4 foals born from the gonadectomized fetuses were dysmature and died during or soon after birth, indicating that fetal gonads might play an essential role in fetal development.
Finding 4: Role of Estrogens
- The study also delved into the production of estrogens by the feto-placental unit from a biosynthesis perspective, discussing the potential role of these hormones in fetal development during the mare’s pregnancy.
Cite This Article
APA
Pashen RL, Allen WR.
(1979).
The role of the fetal gonads and placenta in steroid production, maintenance of pregnancy and parturition in the mare.
J Reprod Fertil Suppl(27), 499-509.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Castration
- Estrogens / blood
- Female
- Gonads / embryology
- Gonads / physiology
- Horses / physiology
- Labor, Obstetric
- Male
- Placenta / physiology
- Pregnancy
- Pregnancy Maintenance
- Pregnancy, Animal
- Progestins / blood
- Steroids / biosynthesis
Citations
This article has been cited 5 times.- Schuler G, Fürbass R, Klisch K. Placental contribution to the endocrinology of gestation and parturition.. Anim Reprod 2018 Jul-Sep;15(Suppl 1):822-842.
- Haneda S, Dini P, Esteller-Vico A, Scoggin KE, Squires EL, Troedsson MH, Daels P, Nambo Y, Ball BA. Estrogens Regulate Placental Angiogenesis in Horses.. Int J Mol Sci 2021 Nov 9;22(22).
- Dhakal P, Tsunoda N, Nambo Y, Taniyama H, Nagaoka K, Watanabe G, Taya K. Circulating activin A during equine gestation and immunolocalization of its receptors system in utero-placental tissues and fetal gonads.. J Equine Sci 2021 Jun;32(2):39-48.
- Raeside JI. A Brief Account of the Discovery of the Fetal/Placental Unit for Estrogen Production in Equine and Human Pregnancies: Relation to Human Medicine.. Yale J Biol Med 2017 Sep;90(3):449-461.
- Stansfield FJ, Nöthling JO, Allen WR. Growth and development of the ovary and small follicle pool from mid fetal life to pre-puberty in the African elephant (Loxodonta africana).. BMC Vet Res 2012 Jul 23;8:119.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
