Vitrification of oocytes and embryos: Finally a recognized technique, but still a source of concern and debate

Even though vitrication was initiated as a viable cryopreservation technique 30 years ago,1,2 we have had to wait more than 20 years before a shi away from conventional controlled-rate slow freezing (SF) toward vitrication occurred. It is now recognized worldwide that vitrication is more eective than the standard SF technique for cryopreservation of oocytes and embryos at different stages of development,3-11 resulting in a doubling of pregnancy rates.3,4 e implementation of this ecient technique gives us the opportunity to change the strategy for embryo transfer and to extend the indications for cryopreservation of oocytes and embryos.