Simplified EM grid vitrification is a convenient and efficient method for mouse mature oocyte cryopreservation.
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.
Kim
Seok Hyun
SH
Department of Obstetrics and Gynecology, Seoul National University, Chongno-gu, Seoul 110-744, Korea.
Ku
Seung-Yup
SY
Sung
Ki Cheong
KC
Kang
Moon Joo
MJ
Kim
Sung Ah
SA
Kim
Hee Sun
HS
Oh
Sun Kyung
SK
Jee
Byung Chul
BC
Suh
Chang Suk
CS
Choi
Young Min
YM
Kim
Jung Gu
JG
Moon
Shin Yong
SY
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