Methanol as a cryoprotectant for equine embryos.

The research examined the use of methanol and glycerol as cryoprotectants for equine embryos, comparing their effectiveness in terms of embryo survival rates.

Research Design and Methodology

• The research involved nonsurgically recovering 43 equine embryos seven to eight days after ovulation.
• The embryos were then randomly divided into two groups for cryopreservation using either methanol or glycerol as cryoprotectants.
• The changes in embryo diameter after exposure to the two cryoprotectants were measured at regular intervals
• The embryos were preserved in a programmable cell freezer, cooled from room temperature (22°C) to -6°C. The embryos were then cooled further to -33°C before being immersed in liquid nitrogen.
• After thawing, the embryos in each group were either cultured for 12 hours prior to transfer or were non-surgically transferred to a mare immediately.”

Findings and Observations

• Upon initial exposure to the cryoprotectant, the diameter of all embryos decreased.
• Embryos exposed to methanol shrank and recovered slightly to 76±8% of their initial diameter while those exposed to glycerol continued to shrink, reaching 57±6% of their original diameter before cryopreservation.
• The study also recorded the survival rates of the embryos till Day 16 of pregnancy which were 38% and 23% for embryos cryopreserved with glycerol or methanol, respectively.
• There wasn’t a discernible difference in the pregnancy rates when embryos were cultured prior to transfer or not.

Conclusion

• The study concluded that while 48% methanol was not harmful to fresh equine embryos, it did not provide any notable advantage over glycerol as a cryoprotectant for equine blastocysts.