Vitrification

Vitrification is a fast-freezing technique in which eggs, embryos or sperm are cooled so rapidly, using a high concentration of protective fluid, that they solidify into a glass-like state rather than forming ice crystals that could damage cells. It has largely replaced older, slower freezing methods in Indian and international fertility laboratories because it is associated with better survival after warming. Slow freezing is an older method that cools material gradually over a longer period; it is now used less often for eggs and embryos, though it may still be used in some laboratory settings, such as for certain sperm samples. Your embryology team can explain which method is used at your clinic.

Also known as: fast freezing, vitrified

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.