Oocyte Cryopreservation Technique

Cryopreservation of human oocytes can be performed by both slow freezing and vitrification. In 1986, the first report of a pregnancy from frozen-thawed oocytes was obtained [1]. Since this report, many efforts were made to improve the efficiency of the cryopreservation protocols, both for slow-freezing and vitrification. It was more than one decade later that a live birth was described after oocyte vitrification [2] and it was only in 2005 that a highly efficient and reproducible vitrification protocol for human oocytes was obtained [3]. Both methods are currently still applied although the results obtained with vitrification appear to be superior to the ones obtained with slow-freezing [4].