Cryopreservation of human oocytes

Three different methods were used for freezing human excess oocytes (320 frozen, 205 thawed) in our IVF programme and the results of these methods were compared. A high fertilization rate (75%) could be achieved after thawing, using 1,2 propanediol as a cryoprotectant. Polyploidy rates of 20% and 40% were observed using DMSO and 1,2-propanediol as cryoprotectants, respectively. Using the ultracooling method, the survival rate was poor (4%).