title: Simplified EM grid vitrification is a convenient and efficient method for mouse mature oocyte cryopreservation.
abstract: This study was performed to evaluate the efficiency of simplified EM grid vitrification, skipping the step of removing the cryoprotectant (5.5M EG + 1.0M sucrose) droplet on the grid after loading oocytes, compared to conventional cryopreservation protocols for mouse mature oocytes. Firstly, the recovery, survival, fertilization and hatching rates of simplified EM grid vitrification were compared with those of the slow freezing method using 1.5M DMSO. Then, conventional EM grid vitrification was compared with simplified EM grid vitrification. Simplified EM grid vitrification showed higher survival, fertilization and hatching rates than those of the slow freezing method (85.6% vs. 63.2%; 51.0% vs. 22.3%; 38.7% vs. 12.5%, p < 0.01, respectively). Moreover, simplified EM grid vitrification showed higher recovery, survival and fertilization rates than those of conventional EM grid vitrification (100% vs. 95.0%, p=0.024; 90.0% vs. 78.9%, p=0.033; 56.7% vs. 38.7%, p=0.021, respectively). Hatching rate tended to be higher for simplified EM grid vitrification compared to conventional EM grid vitrification (41.1% vs. 24.1%). In conclusion, simplified EM grid vitrification is a convenient and efficient method for cryopreservation of mouse mature oocytes, compared to conventional EM grid vitrification and slow freezing methods.
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University, Chongno-gu, Seoul 110-744, Korea.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Seung-Yup
authors.initials: SY
authors.lastname: Ku
authors.forename: Ki Cheong
authors.initials: KC
authors.lastname: Sung
authors.forename: Moon Joo
authors.initials: MJ
authors.lastname: Kang
authors.forename: Sung Ah
authors.initials: SA
authors.lastname: Kim
authors.forename: Hee Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Sun Kyung
authors.initials: SK
authors.lastname: Oh
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Jee
authors.forename: Chang Suk
authors.initials: CS
authors.lastname: Suh
authors.forename: Young Min
authors.initials: YM
authors.lastname: Choi
authors.forename: Jung Gu
authors.initials: JG
authors.lastname: Kim
authors.forename: Shin Yong
authors.initials: SY
authors.lastname: Moon
mesh_terms: D000818:Animals; D002470:Cell Survival; D015925:Cryopreservation / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009865:Oocytes / Q000166:cytology*; D011247:Pregnancy