In vitro equine embryo production using air-dried spermatozoa, with different activation protocols and culture systems.

This research study explores the effectiveness of using air-dried horse sperm for in vitro embryo development. The study finds that the key factors facilitating better embryo development include a specific type of sperm activation and an in vivo cultural system.

Research Goal

The main objective of the study was to ascertain the viability of using air-dried spermatozoa for in vitro horse embryo production. The research also examined whether sperm extract activation and in vivo culture could enhance the process of embryo production.

Methodology

• The study used both cooled spermatozoa as the control and air-dried spermatozoa stored for different time frames—2, 14, or 28 days—for intra-cytoplasmic sperm injection.
• Two methods were used for oocyte activation: sperm extract activation and the use of a substance called ionomycin.
• The embryos were then either cultured in vitro or in vivo in a mare’s oviduct for a period of 7 days.
• In cases where in vivo culture was implemented, the researchers examined sperm DNA fragmentation via the sperm chromatin dispersion test.

Results

• The study observed a higher cleavage rate in embryos produced via in vitro culture when sperm extract activation was used.
• There were no significant differences in embryo development between the two activators, nor were differences significant between sperm storage periods.
• The use of cooled spermatozoa resulted in the development of blastocysts, while embryos developed to the morulae stage when 28-day air-dried sperm and ionomycin-activated oocytes were used in an in vivo culture system.
• Sperm DNA fragmentation did not show any significant correlation with the cleavage rate nor the embryo recovery rate when in vivo culture was employed.

Conclusion

• The research concluded that in vitro equine embryos can effectively be produced using air-dried sperm stored for several weeks.
• Although sperm extract activation was seen to improve the cleavage rate, it did not enhance overall embryo development.
• In vivo culture was found to yield intrauterine stage embryos, illustrating the importance of a suitable culture system in the in vitro embryo production process.