In vitro comparisons of two cryopreservation techniques for equine embryos: slow-cooling and open pulled straw (OPS) vitrification.

The article focuses on comparing the viability of equine embryos after being preserved using two different techniques: slow-cooling and open pulled straw (OPS) vitrification. The study suggests that the OPS vitrification technique is as effective as the slow-cooling method, however, calls for these findings to be validated by further studies involving the transfer of vitrified embryos to recipient mares.

Objective of the Research

The research was designed to compare the survival rate of 6.5- and 6.75-day-old equine embryos after they were preserved using two different cryopreservation techniques: slow-cooling and open pulled straw (OPS) vitrification. The ultimate purpose was to determine whether OPS vitrification is as efficient as the traditionally used slow-cooling method for the cryopreservation of equine embryos.

Methods and Procedures

• Eighteen embryos were preserved using the slow-cooling method. These embryos were placed in modified PBS embedded with increasing concentration of glycerol. The preserved embryos were then kept in a programmable freezer and subsequently plunged into liquid nitrogen for freezing.
• Twenty embryos were preserved using the OPS vitrification method. These were exposed sequentially to solutions of certain concentrations of dimethyl-sulfoxide (DMSO), ethylene glycol (EG) and sucrose before being plunged into liquid nitrogen.
• After thawing, the embryos from both procedures were cultured in synthetic oviduct fluid (SOF) medium for 3 hours and evaluated.

Results and Findings

• There was no significant difference observed from the mean diameter, morphological grade and the percentage of degenerate embryos after 3 hours of culture for both the slow-cooling and OPS vitrification methods.
• The percentage of dead cells per embryo was similar for both techniques, with a roughly equivalent percentage of cells entering S-phase, an important phase of the cell cycle, for embryos from both methods.
• These findings led to a preliminary conclusion that the OPS vitrification technique may be as efficient as the slow-cooling method for the cryopreservation of equine embryos.

Further Research

According to the researchers, these results need to be validated by additional studies that involve the transfer of OPS vitrified embryos to recipient mares. This would provide a clearer understanding of the effectiveness of the OPS vitrification method in a real-world scenario.