title: Comparison of spindle and chromosome configuration in in vitro- and in vivo-matured mouse oocytes after vitrification.
abstract: OBJECTIVE
  To compare the cytogenetic changes in in vitro- and in vivo-matured oocytes after vitrification.
  
  
  METHODS
  In vitro experiments using murine model.
  
  
  METHODS
  Animal model study in university laboratory.
  
  
  METHODS
  CD-1 mice.
  
  
  METHODS
  In vitro maturation and vitrification of oocytes.
  
  
  METHODS
  Post-warming survival, analysis of spindle and chromosome configurations, aneuploidy screening of parthenogenetically activated oocytes, extent of DNA fragmentation, and early embryonic development after IVF.
  
  
  RESULTS
  Eighty percent of germinal vesicle-stage oocytes matured after in vitro maturation and were cryopreserved by vitrification (n = 354). There was no significant difference in the post-warming survival of in vitro- and in vivo-matured oocytes (94.1% vs. 91.8%, respectively). The majority of in vitro- and in vivo-matured oocytes maintained normal meiotic spindle morphology and chromosome alignment (88.2% vs. 86.9%, respectively) after vitrification and the incidence of aneuploidy was not increased (11.5% vs. 9.3%). However, in vitro-matured oocytes showed a higher rate of DNA fragmentation after vitrification compared to in vivo-matured oocytes. After vitrification, the cleavage and blastocyst formation rates of in vitro-matured oocytes were significantly lower than those of in vivo-matured oocytes (37.0% vs. 60.0% and 5.4% vs. 18.9%, respectively).
  
  
  CONCLUSIONS
  Vitrification of in vitro-matured mouse oocytes results in high survival rates, normal meiotic spindle and chromosome alignment, and no increased incidence of aneuploidy. A possible cause of the reduced developmental competence of in vitro-matured and vitrified oocytes may be due to DNA fragmentation.
authors.affiliation: Division of Reproductive Biology, Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada.
authors.forename: Jack Y J
authors.initials: JY
authors.lastname: Huang
authors.forename: Hai Ying
authors.initials: HY
authors.lastname: Chen
authors.forename: Joseph You Sup
authors.initials: JY
authors.lastname: Park
authors.forename: Seang Lin
authors.initials: SL
authors.lastname: Tan
authors.forename: Ri-Cheng
authors.initials: RC
authors.lastname: Chian
mesh_terms: D000782:Aneuploidy; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D033481:Chromosomes, Mammalian / Q000235:genetics*; D015925:Cryopreservation; D053938:DNA Fragmentation; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism*