Beta-mercaptoethanol supplementation of in vitro maturation medium does not influence nuclear and cytoplasmic maturation of equine oocytes.

This research article explores the impact of antioxidant Beta-mercaptoethanol (BME) supplementation in the maturation medium for equine oocytes. The results reveal that the addition of BME at both common and high concentrations had no significant effect on the nuclear and cytoplasmic maturation of equine oocytes.

Introduction to the Research

• The study begins with the observation that the efficiency of in vitro embryo production in horses is not as high as in other species.
• The research notes prior scientific evidence that oxidative stress negatively impacts the culture of embryos and oocytes.
• In the pursuit to minimize oxidative stress, antioxidants like low-molecular thiol compounds, particularly Beta-mercaptoethanol (BME), have been incorporated into the culture media. Previous studies have evidenced the improvement BME brings about in maturation and embryo development in multiple species.

Aim of the Research

• The primary objective was to determine whether Beta-mercaptoethanol (BME), when added to maturation medium at common (0.1 mM) and high (0.7 mM) concentration levels, would enhance equine oocyte maturation.

Methodology

• Equine oocytes sourced from slaughterhouse ovaries were used for the experiment.
• The criteria for assessing nuclear and cytoplasmic maturation was Meiotic configuration after in vitro maturation (IVM) and early embryo production post intracytoplasmic sperm injection (ICSI).
• The experiment was performed over 1,076 oocytes in two sessions. They were stained with Hoechst 33342 and assessed for nuclear stage after 26 hours of IVM, and afterward, the MII oocytes were fertilized by ICSI.
• Cleavage rates were measured post 60 hours of their culture.

Results of the Research

• The results did not echo previous results recorded for other species. The introduction of BME into the medium did not significantly influence the maturation rates nor the cleavage rates after ICSI.
• The oocytes’ maturation rates in the control group was 51.9%, similar to those in the BME 0.1 mM and BME 0.7 mM groups, which were 55.6% and 55.1% respectively.
• The cleavage rates post ICSI of the control group were comparable to the BME groups, with percentages of 38.6%, 38.5%, and 41.3% respectively.

Conclusion

• In conclusion, it was determined that Beta-mercaptoethanol (BME) supplementation at 0.1 and 0.7 mM to the maturation medium under the experimental culture conditions did not affect the nuclear and cytoplasmic maturation of equine oocytes.