Benefits and constraints of vitrification technologies for cryopreservation of bovine in vitro fertilized embryos

Cryopreservation is the use of ultra-low temperatures to preserve whole living cells and tissues in order to retain their structural integrity and maintain their physiological viability. It enables long term storage of cells in order to circumvent the need for continuous in vitro culture. When cryopreserving bovine embryos there are two means of cryopreservation: slow programmable freezing and vitrification. While controlled-rate and slow freezing can be applied widely to in vivo derived-embryos, this methodology remains less successful for embryos produced in vitro. Vitrification is an alternative technique that minimizes damage due to ice crystal formation and which offers great potential for banking these delicate cells. Examples of circumstances in which this is beneficial include when in vitro fertilization results in more embryos than is necessary for fresh embryo transfer, when conditions are not suitable for immediate embryo transfer, or when transportation of embryos is required prior to use. This paper summarizes the principle of vitrification and addresses its relative strengths and limitations as a means of conserving embryos to facilitate bovine reproductive technologies. Prospective improvements to enhance the efficiency of vitrification and perspectives on its future implementation are also discussed.