Cryopreservation of ICR mouse oocytes:: improved post-thawed preimplantation development after vitrification using Taxol™, a cytoskeleton stabilizer

Objective: To establish an effective cryopreservation method. Design: In vitro model study. Setting: Infertility Medical Center, Pochon CHA University. Animal(s): Four-week-old ICR mice superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin. Intervention(s): Vitrified-thawed oocytes were fertilized and subsequently cultured in vitro. Main Outcome Measure(s): Post-thawed development, chromosome/spindle normalities, and blastocyst quality. Result(s): More cumulus-enclosed oocytes were fertilized and developed to the 8-cell stage after vitrification and thawing than denuded oocytes. However, cryopreserved oocytes of both types had lower spindle and chromosome normalities than fresh oocytes, which resulted in reduced developmental competence after thawing. The addition of 1 muM of Taxol(TM), a cytoskeleton stabilizer, to vitrification solution greatly promoted the blastocyst formation of vitrified-thawed oocytes, compared with no addition (24.0% vs. 58.6%). No difference in blastocyst quality, which was evaluated by blastomere and inner cell mass cell numbers and inner cell mass cell per trophoblast ratio, was found between fresh oocytes and oocytes vitrified with Taxol(TM). Conclusion(s): A vitrification solution consisting of 5.5 M ethylene glycol, 1.0 M sucrose, 10% fetal bovine serum, and 1 muM Taxol(TM) greatly improved post-thawed development of vitrified oocytes. (Fertil Steril(R) 2001;75:1177-84. (C) 2001 by American Society for Reproductive Medicine.).