Clinical insights: Assisted reproductive technologies

Stout, T.A.E.

doi:10.1111/evj.13099

Cited by 8 publications

(3 citation statements)

References 18 publications

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“…Embryo flushing (EF), recovery and transfer of in vivo derived embryos is a common assisted reproductive technique performed worldwide in the mare 1–3 . Most veterinary surgeons administer a luteolytic drug, prostaglandin F 2α (PGF), at the end of EF to induce oestrus 4–6 .…”

Section: Introductionmentioning

confidence: 99%

Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Martínez‐Boví,

Sala‐Ayala,

Querol‐Paajanen

et al. 2024

Equine Veterinary Journal

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BackgroundPGF2α is commonly given at the end of embryo flushing (EF) to shorten the interval to the next oestrus and ovulation.ObjectivesTo determine the effect of repeated EF on plasma progesterone concentration, percentage of mares with endometritis, unwanted pregnancy and subsequent fertility in mares flushed without the use of PGF2α.Study designControlled experiments.MethodsNine mares were inseminated in seven consecutive cycles (n = 63), to either perform an EF (n = 54) 7–9 days after ovulation or left pregnant (n = 9). PGF2α was not used to induce oestrus. Ultrasound examination and blood sampling were performed just before the EF and 72 h later to determine changes in progesterone concentration and signs of endometritis.ResultsThe overall percentage of positive EF/pregnancy was 55.5% (30/54) and 66.7% (6/9), respectively. The likelihood of pregnancy/positive EF in the first three cycles was 55.5% (15/29). This was not different (p > 0.1) from the fertility of the last four cycles (69.4%, 25/36). In five EF cycles (9.3%), mares had signs of endometritis and early luteolysis (progesterone <2 ng/mL) 72 h after EF. The reduction in progesterone concentration by 72 h after EF was greater (p < 0.05) for Day 9 (−2.3 ± 0.7 ng/mL) than Day 7 (−1.0 ± 0.8 ng/mL) or Day 8 (−1.3 ± 1.1 ng/mL) cycles. The progesterone concentration in non‐flushed mares did not vary significantly during the sampled period (Day 7–12). There were 5 cycles in which the donor mare remained pregnant after the EF, although four were from a single mare.Main limitationsThe mare population was limited to barren and maiden mares. The cycle order and operator allocation to each EF were not randomised.ConclusionsEF induces a subtle, but significant reduction in progesterone concentrations compared with non‐EF cycles. However, the percentage of mares with EF‐induced full luteolysis is low (9.3%). The fertility of mares after repeated EF without administration of PGF2α was unaffected; however, there is a considerable risk of unwanted pregnancy (5/27 = 18.5%) in donors from which an embryo was not recovered.

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Section: Introductionmentioning

confidence: 99%

Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Martínez‐Boví,

Sala‐Ayala,

Querol‐Paajanen

et al. 2024

Equine Veterinary Journal

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“…To date, the pre‐ and post‐natal studies suggest that developmental programming of equine physiological phenotype by environmental conditions in utero tracks from intra‐ to extra‐uterine life and is related to alterations in resource allocation to the fetus, mediated, in part, by the accompanying changes in placental development (Table ). This potential role of the placenta in developmental programming also has implications for the phenotype of foals produced by assisted reproductive technologies because use of in vitro culture and a recipient uterus unprimed by a natural embryo produces an abnormal environment for development that can alter embryonic cell fate decisions and trophoblast differentiation epigenetically .…”

Section: Developmental Programming Of Physiological Phenotypementioning

confidence: 99%

Physiological development of the equine fetus during late gestation

Fowden

Giussani

Forhead

2019

Equine Veterinary Journal

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In many species, the pattern of growth and physiological development in utero has an important role in determining not only neonatal viability but also adult phenotype and disease susceptibility. Changes in fetal development induced by a range of environmental factors including maternal nutrition, disease, placental insufficiency and social stresses have all been shown to induce adult cardiovascular and metabolic dysfunction that often lead to ill health in later life. Compared to other precocious animals, much less is known about the physiological development of the fetal horse or the longerterm impacts on its phenotype of altered development in early life because of its inaccessibility in utero, large size and long lifespan. This review summaries the available data on the normal metabolic, cardiovascular and endocrine development of the fetal horse during the second half of gestation. It also examines the responsiveness of these physiological systems to stresses such as hypoglycaemia and hypotension during late gestation. Particular emphasis is placed on the role of the equine placenta and fetal endocrine glands in mediating the changes in fetal development seen towards term and in response to nutritional and other environmental cues. The final part of the review presents the evidence that the early life environment of the horse can alter its subsequent metabolic, cardiovascular and endocrine phenotype as well as its postnatal growth and bone development. It also highlights the immediate neonatal environment as a key window of susceptibility for programming of equine phenotype. Although further studies are needed to identify the cellular and molecular mechanisms involved, developmental programming of physiological phenotype is likely to have important implications for the health and potential athletic performance of horses, particularly if born with abnormal bodyweight, premature or dysmature characteristics or produced by assisted reproductive technologies, indicative of an altered early life environment.

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“…In vitro embryo production (IVP) is a rapidly expanding field in the equine breeding industry, increasing the efficiency of breeding programs [ 1 ] and contributing to the production of live foals from valuable mares and stallions which could not otherwise produce progeny using traditional breeding methods [ 2 ]. The retrieval of immature oocytes from antral follicles of varying sizes and developmental stages from standing sedated mares is an important source of female gametes for IVP.…”

Section: Introductionmentioning

confidence: 99%

Transcriptome Signature of Immature and In Vitro-Matured Equine Cumulus–Oocytes Complex

de la Fuente,

Scoggin,

Bradecamp

et al. 2023

IJMS

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Maturation is a critical step in the development of an oocyte, and it is during this time that the oocyte advances to metaphase II (MII) of the meiotic cycle and acquires developmental competence to be fertilized and become an embryo. However, in vitro maturation (IVM) remains one of the limiting steps in the in vitro production of embryos (IVP), with a variable percentage of oocytes reaching the MII stage and unpredictable levels of developmental competence. Understanding the dynamics of oocyte maturation is essential for the optimization of IVM culture conditions and subsequent IVP outcomes. Thus, the aim of this study was to elucidate the transcriptome dynamics of oocyte maturation by comparing transcriptomic changes during in vitro maturation in both oocytes and their surrounding cumulus cells. Cumulus–oocyte complexes were obtained from antral follicles and divided into two groups: immature and in vitro-matured (MII). RNA was extracted separately from oocytes (OC) and cumulus cells (CC), followed by library preparation and RNA sequencing. A total of 13,918 gene transcripts were identified in OC, with 538 differentially expressed genes (DEG) between immature OC and in vitro-matured OC. In CC, 13,104 genes were expressed with 871 DEG. Gene ontology (GO) analysis showed an association between the DEGs and pathways relating to nuclear maturation in OC and GTPase activity, extracellular matrix organization, and collagen trimers in CC. Additionally, the follicle-stimulating hormone receptor gene (FSHR) and luteinizing hormone/choriogonadotropin receptor gene (LHCGR) showed differential expressions between CC-MII and immature CC samples. Overall, these results serve as a foundation to further investigate the biological pathways relevant to oocyte maturation in horses and pave the road to improve the IVP outcomes and the overall clinical management of equine assisted reproductive technologies (ART).

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Clinical insights: Assisted reproductive technologies

Cited by 8 publications

References 18 publications

Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Physiological development of the equine fetus during late gestation

Transcriptome Signature of Immature and In Vitro-Matured Equine Cumulus–Oocytes Complex

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Clinical insights: Assisted reproductive technologies

Cited by 8 publications

References 18 publications

Effects of repeated embryo flushing without PGF2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Effects of repeated embryo flushing without PGF2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Physiological development of the equine fetus during late gestation

Transcriptome Signature of Immature and In Vitro-Matured Equine Cumulus–Oocytes Complex

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Product

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Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares

Effects of repeated embryo flushing without PGF_2α administration on luteal function, percentage of unwanted pregnancy and subsequent fertility in mares