title: Effect of using slush nitrogen (SN2) on development of microsurgically manipulated vitrified/warmed mouse embryos.
abstract: BACKGROUND
  This study evaluated the effect of vitrification using slush nitrogen (SN(2)) on cryopreservation of micromanipulated mouse embryos.
  
  
  METHODS
  The zona pellucida of 4-cell embryos was either left intact or dissected or dissected with biopsy of an intact blastomere. In a second study, a blastomere was destroyed and either removed (removed group) or not removed (remained group) prior to vitrification/freezing. The micromanipulated embryos were equilibrated and loaded into an open pulled straw (OPS), and plunged into liquid nitrogen (LN(2)) or SN(2).
  
  
  RESULTS
  When using LN(2) vitrification, recovery and blastocyst formation rates of embryos were lower for zona pellucida-opened and/or blastomere-biopsied embryos compared with zona pellucida-intact embryos. Using SN(2) for vitrification resulted in increased survival and development of vitrified/warmed embryos in both the zona pellucida-opened and blastomere-biopsy groups. Similar results were observed when using embryos with a destroyed blastomere either removed or left remaining before vitrification. However, the number of total and apoptotic cells were similar for both LN(2) and SN(2). In addition, using SN(2) increased the rate of intact recovery and blastocyst formation in warmed hemi-8-cell embryos derived from the same embryo.
  
  
  CONCLUSIONS
  These results suggest that vitrification using SN(2) is useful in cryopreservation of micromanipulated embryos obtained from a variety of programs, including assisted hatching, preimplantation genetic diagnosis and nuclear transfer.
authors.affiliation: Fertility Center of CHA General Hospital, CHA Research Institute, Pochon CHA University, 606-5 Yeoksam-dong, Gangnam-gu, Seoul 135-081, Republic of Korea. drleedr@cha.ac.kr
authors.forename: Dong Ryul
authors.initials: DR
authors.lastname: Lee
authors.forename: Yun Hee
authors.initials: YH
authors.lastname: Yang
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Eum
authors.forename: Jin Seong
authors.initials: JS
authors.lastname: Seo
authors.forename: Jung Jae
authors.initials: JJ
authors.lastname: Ko
authors.forename: Hyung Min
authors.initials: HM
authors.lastname: Chung
authors.forename: Tae Ki
authors.initials: TK
authors.lastname: Yoon
mesh_terms: D000818:Animals; D017209:Apoptosis; D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology* / Q000187:drug effects*; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D008866:Microsurgery; D009584:Nitrogen / Q000494:pharmacology*; D015044:Zona Pellucida / Q000187:drug effects
chemical_list: D009584:Nitrogen