Cryopreservation of human failed maturation oocytes shows that vitrification gives superior outcomes to slow cooling.

Abstract This study investigated whether failed maturation oocytes could be used to evaluate different cryopreservation procedures. A total of 289 failed maturation oocytes (GV and MI stages), obtained from 169 patients undergoing IVF treatment (mean age 33.84 ± 5.0) were divided into two different slow-cooling groups (1.5 mol/l 1,2-propanediol + 0.2 mol/l sucrose in either NaCl (group A) or choline chloride (ChCl) (group B) based cryopreservation solutions) and one vitrification group (15% ethylene glycol + 15% dimethyl sulphoxide). Survival rate, in vitro maturation (IVM) rate, fertilization and developmental rate of cryopreserved oocytes were assessed. Regardless of the stage at which cryopreservation was performed (GV + MI), the slow cooling with ChCl based medium always gave significantly lower survival rate than the slow cooling in NaCl based medium ( p  = 0.01) and vitrification ( p p