title: Comparison of the survival of human biopsied embryos after cryopreservation with four different methods using non-transferable embryos.
abstract: BACKGROUND
  The standard embryo cryopreservation method is still less than optimal for biopsied embryos. The aim of this study was to compare the survival of biopsied embryos cryopreserved with four different methods using non-transferable embryos.
  
  
  METHODS
  Abnormal embryos from one or three pronuclei and spare embryos of grade 3 and 4 were used for this study. Non-biopsied embryos were cryopreserved using the standard method as control. Biopsied embryos were cryopreserved using four methods as follows: standard method, modified freezing method, modified thawing method and vitrification. Blastomere survival and blastulation of frozen-thawed embryos were compared between the different methods.
  
  
  RESULTS
  The proportion of embryos with > or = 50% blastomere survival and total blastomere survival rate of biopsied embryos were significantly higher with vitrification than the other three methods. Both the modified freezing and modified thawing methods had significantly higher embryo survival and total blastomere survival rates than standard methods. However, there was no significant difference in blastulation of surviving embryos in all the five groups.
  
  
  CONCLUSIONS
  Non-transferable embryos derived from clinical IVF/ICSI are useful for evaluation of the optimal freezing procedures for biopsied embryos. Vitrification increases the survival rate of human biopsied embryos above standard and modified cryopreservation methods.
authors.affiliation: Center for Reproductive Medicine, Department of Obstetrics and Gynecology, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China. sunnyjenny@yahoo.com.cn
authors.forename: W T
authors.initials: WT
authors.lastname: Zheng
authors.forename: G L
authors.initials: GL
authors.lastname: Zhuang
authors.forename: C Q
authors.initials: CQ
authors.lastname: Zhou
authors.forename: C
authors.initials: C
authors.lastname: Fang
authors.forename: J P
authors.initials: JP
authors.lastname: Ou
authors.forename: T
authors.initials: T
authors.lastname: Li
authors.forename: M F
authors.initials: MF
authors.lastname: Zhang
authors.forename: X Y
authors.initials: XY
authors.lastname: Liang
mesh_terms: D001706:Biopsy; D001755:Blastocyst / Q000502:physiology; D001757:Blastomeres / Q000502:physiology; D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology*; D006801:Humans