title: High survival rate of bovine oocytes matured in vitro following vitrification.
abstract: Improving pregnancy rates associated with the use of cryopreserved human oocytes would be an important advance in human assisted reproductive technology (ART). Vitrification allows glasslike solidification of a solution without ice crystal formation in the living cells. We have attempted to improve the survival rates of oocytes by a vitrification technique using bovine models. In vitro matured oocytes with or without cumulus cells were vitrified with either 15.0% (v/v) ethylene glycol (EG) + 15% (v/v) dimethylsulfoxide (DMSO) + 0.5 M sucrose or 15% (v/v) EG + 15% (v/v) 1,2-propanediol (PROH) + 0.5 M sucrose, using 'Cryotop' or 'thin plastic sticker', respectively. The oocyte survival rates after vitrifying-warming, and the capacity for fertilization and embryonic development were examined in vitro. The rate of embryonic development to blastocyst was significantly higher (P<0.05) in the oocytes vitrified with 15% (v/v) EG + 15% (v/v) PROH + 0.5 M sucrose than in the oocytes vitrified with 15% (v/v) EG + 15% (v/v) DMSO + 0.5 M sucrose (7.4% +/- 4.1 vs. 1.7% +/- 3.0, respectively). Oocytes vitrified without cumulus cells had a higher survival rate after thawing and a superior embryonic developmental capacity compared with oocytes vitrified with cumulus cells. Prolonged pre-incubation time after thawing adversely affected the rates of embryonic cleavage and development. These results indicate that in vitro matured bovine oocytes can be vitrified successfully with the mixture of the cryoprotectants, EG + PROH, the absence of cumulus cells for vitrification does not affect oocyte survival rate after warming, and vitrified and warmed oocytes do not require pre-incubation before in vitro fertilization.
authors.affiliation: Division of Reproductive Biology, Department of Obstetrics and Gynecology, McGill University, Montreal, Canada. ri-cheng.chian@muhc.mcgill.ca
authors.forename: Ri-Cheng
authors.initials: RC
authors.lastname: Chian
authors.forename: Masashige
authors.initials: M
authors.lastname: Kuwayama
authors.forename: Leonard
authors.initials: L
authors.lastname: Tan
authors.forename: Justin
authors.initials: J
authors.lastname: Tan
authors.forename: Osamu
authors.initials: O
authors.lastname: Kato
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods*; D002470:Cell Survival; D003451:Cryoprotective Agents / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D046149:Embryo Culture Techniques / Q000379:methods*; D004622:Embryo, Mammalian / Q000166:cytology; D019855:Ethylene Glycol / Q000737:chemistry; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism; D011409:Propylene Glycols / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry
chemical_list: D003451:Cryoprotective Agents; D011409:Propylene Glycols; D013395:Sucrose; D019855:Ethylene Glycol; D004121:Dimethyl Sulfoxide