Vitrification is a method in which not only cells but also the whole solution is solidified without the crystallization of ice. The vitrification method has advantages over the slow freezing method. Injuries related to ice is less likely to occur, embryo survival is more likely if the embryo treatment is optimized, and embryos can be cryopreserved by a simple method in a short time and cost effective without a programed freezer.
(1) Successful cryopreservation of human embryos was first reported in 1983 by Trounson and Mohr using days 2 and 3 embryos that had been slow-cooled using dimethyl sulphoxide (DMSO). Subsequent modifications of the technique had taken place such as introducing 1,2-propanediol and sucrose as cryoprotectants.
(2) Slow-cooling to −30 °C prior to plunging into liquid nitrogen. All these resulted in the introduction of cryopreservation as a standard method offered by virtually every IVF program world-wide.
(3) Recently, lots of reproductive clinics, using embryos and blastocysts cryopreservation depend on vitrification. Vitrification is an ultra-rapid method of cryopreservation whereby the embryo is transitioned from 37 to −196 °C in <1 s, resulting in extremely fast rates of cooling. High concentrations of cryoprotectants together with rapid cooling rates are essential to cryopreserve embryos in a vitrified, glass-like state.
Vitrification is a cryopreservation technique that leads to a glass-like solidification. Oocyte, zygote, embryo and blastocyst freezing by vitrification method for cryopreservation have been used for many years beside sperms preservation.