Overnight holding aids in selection of developmentally competent equine oocytes.
Abstract: The demand for equine in vitro produced embryos has increased over the last decade. The aim of this study was to compare the effects of an extended IVM or a prolonged period before fertilization, including holding time, on equine immature oocyte developmental competence. Oocytes, collected from abattoir-derived ovaries, were divided into 4 groups: H0/24 (n = 165) 0 h holding + standard 24-26 h IVM; H8/36 (n = 160) 8 h holding + 36 h IVM; H20/24 (n = 187) 20 h holding + 24 h IVM; H0/44 (n = 164) 0 h holding + 44 h IVM. Oocytes matured to MII were fertilized by intracytoplasmic sperm injection (ICSI) and cultured for 10 days. The oocyte degeneration rate was higher (P < 0.05) for H20/24 than the other groups (H0/24 38.2 %, H8/36 43.1 %, H20/24 54.5 %, H0/44 32.9 %). Cleavage was higher (P < 0.05) in H20/24 (70 %) compared to H0/24 (45 %) and H8/36 (54 %) but not to H0/44 (63 %). No differences among groups were observed in the number of blastocysts per oocyte. Injected oocytes that reached the blastocysts stage were higher (P < 0.05) for H20/24 (20 %) than H0/24 (7 %) and H0/44 (7 %) but not H8/36 (12 %). For cleaved oocytes, a higher blastocyst rate (P < 0.05) was observed for H20/24 (28 %) than H0/44 (11 %), while H0/24 (15 %) and H8/36 (21 %) were not different from any group (P > 0.05). Timing of blastocyst development was not different among groups. Overnight holding of equine immature oocytes followed by a standard IVM interval may induce a pre-selection of the most competent oocytes thereby improving cleavage and embryo development rates after ICSI.
Copyright © 2022 Elsevier B.V. All rights reserved.
Publication Date: 2022-09-17 PubMed ID: 36152450DOI: 10.1016/j.anireprosci.2022.107071Google Scholar: Lookup
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- Journal Article
Summary
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The research investigates how different holding and in vitro maturation (IVM) times affect the development of equine (horse) oocytes, or egg cells. The study indicates that leaving immature oocytes in a holding phase overnight before a standard IVM period may improve cell cleavage and embryo development.
Objective of the Research
- The goal of this study was to measure the effect of modified In Vitro Maturation (IVM) timings and an extended period before fertilization, including periods of holding, on the developmental competence of equine oocytes.
- This is important because demand for in vitro produced equine embryos has been rising, so optimizing the process is essential.
Methodology
- The researchers used oocytes collected from ovaries obtained from an abattoir.
- These oocytes were divided into 4 groups based on the duration of holding times and IVM processes. They were designated H0/24, H8/36, H20/24, and H0/44.
- After maturing to the MII phase, these oocytes were fertilized using Intracytoplasmic Sperm Injection (ICSI) and cultured for 10 days.
Findings
- The rate of oocyte degeneration was significantly higher (54.5%) for the H20/24 group than the others, suggesting this holding period and IVM timing may be less successful.
- Oocyte cleavage, a vital process in successful embryo development, was highest (70%) in the H20/24 group, followed by H0/44 (63%), H8/36 (54%), and H0/24 (45%).
- Blastocysts development per oocyte did not differ among the groups.
- The percentage of injected oocytes reaching the blastocyst stage was highest for the H20/24 group (20%) compared to H0/24 and H0/44, both with 7%, but comparable to H8/36 (12%).
- A higher blastocyst rate was observed for cleaved oocytes in the H20/24 group (28%) than the H0/44 group (11%).
Conclusion
- The study concludes that an overnight holding phase followed by a standard IVM period may result in pre-selection of more competent oocytes, as evidenced by higher cleavage and embryo development rates after Intracytoplasmic Sperm Injection (ICSI).
Cite This Article
APA
Merlo B, Del Prete C, Mari G, Iacono E.
(2022).
Overnight holding aids in selection of developmentally competent equine oocytes.
Anim Reprod Sci, 245, 107071.
https://doi.org/10.1016/j.anireprosci.2022.107071 Publication
Researcher Affiliations
- Department of Veterinary Medical Sciences, University of Bologna, via Tolara di Sopra 50, 40064 Ozzano Emilia, BO, Italy. Electronic address: barbara.merlo@unibo.it.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Via Federico Delpino 1, 80137 Napoli, NA, Italy.
- Department of Veterinary Medical Sciences, University of Bologna, via Tolara di Sopra 50, 40064 Ozzano Emilia, BO, Italy; National Institute of Artificial Insemination, University of Bologna, via Gandolfi 16, 40057 Cadriano, BO, Italy.
- Department of Veterinary Medical Sciences, University of Bologna, via Tolara di Sopra 50, 40064 Ozzano Emilia, BO, Italy.
MeSH Terms
- Animals
- Blastocyst
- Embryonic Development
- Horses
- In Vitro Oocyte Maturation Techniques / veterinary
- Male
- Oocytes
- Semen
- Sperm Injections, Intracytoplasmic / veterinary
Conflict of Interest Statement
Declarations of interest None.
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