[Successful direct transfer of a deep frozen-thawed equine embryo].

This study represents the first known successful birth of a live foal after transfer of a previously frozen and then thawed equine embryo, achieved through specific preservation and synchronization techniques.

Methodology

• The research was conducted on two mares. Embryos were flushed out on the 7th day following ovulation.
• These embryos were then frozen using a conventional slow freezing procedure. This procedure uses phosphate buffered (PBS) saline supplemented with 10% FCS, 1.5 mol/L ethylene glycol, and 0.25 mol/L sucrose. These chemicals act as cryoprotectants, substances used to protect biological tissue from freezing damage.

Storage and Thawing

• One of the two embryos was stored in liquid nitrogen for 10 months. Liquid nitrogen was used for storage because of its very low temperature (-196 degrees Celsius), which helps in the preservation of the embryo.
• This embryo was thawed, or slowly brought back to normal temperature. This thawing process is a delicate operation as the cells of the embryos can be potentially damaged by ice crystal formation if done improperly.

Transfer and Result

• The thawed embryo was then transferred directly into a synchronized recipient. This means the recipient mare’s reproductive cycle was manipulated in such a way that it is in sync with the donor’s cycle at the time of embryo production. This synchronization improves the chances of successful pregnancy.
• This process was done without any dilution of the cryoprotectant or any quality examination of the embryo.
• This transfer resulted in the birth of a live female foal, marking it the first time a life was born through this procedure.

Significance

• The study’s approach to cryopreservation and transfer of equine embryos could have wide implications for veterinary medicine and horse breeding. It can allow for genetic material to be stored and used in the long term, and open possibilities for the preservation and propagation of endangered equine species.
• However, further research would be needed to establish the repeatability and efficiency of the demonstrated process.