title: Relationship between meiotic spindle characteristics in human oocytes and the timing of the first zygotic cleavage after intracytoplasmic sperm injection.
abstract: OBJECTIVE
  To investigate the relationship between meiotic spindle characteristics in human oocytes and the timing of the first zygotic cleavage after intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Zygotes that had cleaved to two-cell stage by 27 h post-ICSI were classified as early cleaving and the remainder as late cleaving. Meiotic spindle parameters previously imaged using the PolScope were compared between the two groups.
  
  
  RESULTS
  Of 384 embryos, 163 were classed as early cleaving and 221 as late cleaving. The rate of blastocyst formation or pregnancy by Day 2 embryo transfer was significantly higher following early cleavage than after late cleavage (52.4% vs. 24.4% or 32.6% vs. 11.4%). Spindle areas (108.0 vs. 89.8 μm(2)), lengths (14.7 vs. 13.4 μm) and PolScope retardance were also significantly greater in the early cleaving group.
  
  
  CONCLUSIONS
  Meiotic spindle parameters determine the timing of the first zygotic cleavage and are strong indicators of human embryo developmental potential.
authors: IVF Nagata Clinic, Fukuoka, 810-0001, Japan.
authors: Hiroyuki
authors: H
authors: Tomari
authors: Kou
authors: K
authors: Honjou
authors: Yumi
authors: Y
authors: Nagata
authors: Toshitaka
authors: T
authors: Horiuchi
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology; D002970:Cleavage Stage, Ovum / Q000166:cytology; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D008540:Meiosis / Q000235:genetics*; D008875:Middle Aged; D009865:Oocytes / Q000166:cytology*; D059705:Polar Bodies / Q000166:cytology; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic; D008941:Spindle Apparatus / Q000235:genetics / Q000502:physiology*; D015053:Zygote / Q000166:cytology*