title: Blastocyst development of 4-cell mouse embryos after laser destruction of one blastomere with or without its microsurgical removal.
abstract: OBJECTIVE
  To study the rate of blastocyst formation in 4-cell mouse embryos after laser destruction of one blastomere, with or without microsurgical removal of the destroyed blastomere.
  
  
  METHODS
  Mouse embryos were randomly allocated to two control and two experimented groups. Control embryos were either non-manipulated (117 embryos) or underwent laser ablation of zona only (114 embryos). Experimented embryos had laser destruction of zona and the adjacent blastomeres. Destroyed blastomeres were either left in situ (115 embryos) or were microsurgically removed (107 embryos). They were cultured in sequential media for 72 h and were assessed for cleavage/morula arrest and blastocyst formation rates.
  
  
  RESULTS
  Embryos arrested at cleavage/morula stages were higher when destroyed blastomeres remained in situ (30.4%) than when they were immediately removed (15.0%, P < 0.05). Blastocysts in the group with immediate removal of the destroyed blastomeres (85%) were significantly higher than when destroyed blastomeres were left in situ (69.6%, P < 0.05). Blastocyst formation in the repaired embryos was significantly lower than the non-manipulated (91.5%) and the manipulated controls (94.8%, P < 0.05). Hatching blastocysts were highest in control embryos with zonal ablation (72.8%). Proportions of hatching/hatched blastocysts in embryos, with or without removal of destroyed blastomeres, were not significantly different (39.3% and 33.9%, respectively). The percentage of embryonic loss during an attempt at microsurgical repair was 6.1%.
  
  
  CONCLUSIONS
  Microsurgical removal of destroyed blastomere was effective in restoring blastocyst development. It could reduce the rate of cleavage/morula arrest.
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. tvutyava@mail.cmu.ac.th
authors.forename: Teraporn
authors.initials: T
authors.lastname: Vutyavanich
authors.forename: Patcharada
authors.initials: P
authors.lastname: Amatyakul
authors.forename: Waraporn
authors.initials: W
authors.lastname: Piromlertamorn
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D001757:Blastomeres / Q000502:physiology*; D046149:Embryo Culture Techniques; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D008866:Microsurgery; D015044:Zona Pellucida / Q000502:physiology