Simple, efficient and successful vitrification of bovine blastocysts using electron microscope grids

Area of Science:

• Veterinary Science
• Embryology
• Cryobiology

Background:

• Cryopreservation of bovine embryos is crucial for livestock breeding and conservation.
• Traditional methods using plastic straws have limitations in optimizing embryo survival rates.
• Electron microscope (EM) grids offer an alternative container for vitrification.

Purpose of the Study:

• To compare the efficacy of EM grids versus plastic straws for vitrifying bovine blastocysts.
• To assess the impact of cryopreservation on embryo survival and hatching rates.
• To evaluate the influence of embryo developmental stage on cryosurvival.

Main Methods:

• In-vitro produced day 7 bovine blastocysts were vitrified using EFS40 solution on either EM grids or plastic straws.
• Embryo survival was evaluated by re-expansion and hatching rates at 24 and 48 hours post-thaw.
• Effects of vitrification solution exposure and chilling injury were assessed.

Main Results:

• Vitrification using EM grids resulted in significantly higher hatching rates (67.8%) at 48 hours compared to straws (53.3%).
• Fast-developing embryos (expanded and early hatching blastocysts) exhibited superior cryotolerance.
• Survival rates for expanded and early hatching blastocysts were significantly higher with EM grids (67.8%, 95.0%) versus straws (53.0%, 65.0%) at 48 hours.

Conclusions:

• Electron microscope (EM) grids are a superior container for vitrifying bovine blastocysts, enhancing post-thaw survival and hatching.
• Embryo developmental stage critically influences cryosurvival, with advanced stages showing better resilience.
• This finding supports the adoption of EM grids for improved efficiency in bovine embryo cryopreservation.