title: Cryopreservation of mature human oocytes by vitrification with ethylene glycol in straws.
abstract: OBJECTIVE
  To examine the effect of vitrification with ethylene glycol (EG) for mature human oocytes in straws.
  
  
  METHODS
  Prospective, randomized, in vitro experiments.
  
  
  METHODS
  Reproductive unit of a university hospital.
  
  
  METHODS
  Immature oocytes from 110 patients undergoing intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  The immature oocytes were incubated to reach metaphase II (MII). The MII oocytes were treated with EG-based cryoprotectants and vitrified in straws. They were diluted in sucrose solutions, inseminated by ICSI, and cultured in vitro.
  
  
  METHODS
  Survival, fertilization, and embryo cleavage.
  
  
  RESULTS
  The survival rates were greater for oocytes pretreated with 1.5 M of EG (65% for 0 minute, 93% for 5 minutes, and 96% for 10 minutes). The oocytes vitrified in 60 and 90 seconds had a greater rate of fertilization than those vitrified in 120 seconds. There were no differences in survival and fertilization for vitrified oocytes diluted by three or four steps. The cleavage rates to the six- to eight-cell stage were comparable with controls. However, no blastocyst formation was observed in vitrified oocytes.
  
  
  CONCLUSIONS
  Vitrification of human oocytes with EG in straws achieves a high rate of survival, fertilization, and early cleavage of embryos. Further studies should be conducted for the improvement of blastocyst formation.
authors.affiliation: Department of Obstetrics and Gynecology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: S U
authors.initials: SU
authors.lastname: Chen
authors.forename: Y R
authors.initials: YR
authors.lastname: Lien
authors.forename: Kh
authors.initials: Kh
authors.lastname: Chao
authors.forename: H F
authors.initials: HF
authors.lastname: Lu
authors.forename: H N
authors.initials: HN
authors.lastname: Ho
authors.forename: Y S
authors.initials: YS
authors.lastname: Yang
mesh_terms: D002470:Cell Survival; D015925:Cryopreservation / Q000295:instrumentation / Q000379:methods*; D019855:Ethylene Glycol; D005260:Female; D006801:Humans; D008677:Metaphase; D009865:Oocytes; D011446:Prospective Studies; D011897:Random Allocation; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D019855:Ethylene Glycol