Establishment of Mouse Oocytes Cryopreservation Program / 대한산부인과학회잡지

ABSTRACT

OBJECTIVE: To establish the optimal cryopreservation method in mouse oocytes. METHODS: Firstly, mouse immature oocytes were exposed to various cryoprotectants, and then cryoprotectant with the best outcome was selected. Secondly, mouse immature oocytes were cryopreserved by either slow freezing and ultra-rapid thawing or vitrification. Finally, in mouse mature oocytes, the five different protocols were compared in their fertilization and hatching rates. RESULTS: 1) 1.5M 1,2-propanediol (PROH) and 1.5M PROH+0.1M sucrose had a higher rate of survival (73.1%, 81.9%) and in vitro maturation (28.2%, 30.1%). 2) Vitrification using 5.5M ethylene glycol (EG) showed significantly higher rate of survival and in vitro maturation, when compared with slow freezing and ultra-rapid thawing using 1.5M PROH+0.1M sucrose (65.9% vs 50.0%, 40.0% vs 28.2%, respectively). 3) In mouse mature oocytes, vitrification using 5.5M EG showed significantly higher survival rate, however, slow freezing and ultra-rapid thawing using 1.5M DMSO was superior to vitrification in view of fertilization rate. CONCLUSIONS: Vitrification showed better outcomes in mouse immature oocytes, but slow freezing and ultra-rapid thawing using 1.5M DMSO may be beneficial in mature oocytes.