title: Developmental prognosis for zygotes based on pronuclear pattern: usefulness of pronuclear scoring.
abstract: OBJECTIVE
  To relate pronuclear patterns (PN) and zygote cytoplasmic appearance and embryo morphology.
  
  
  METHODS
  The usefulness of PN classification described by Tesarik et al. 1999 (patterns p0-5) and Scott et al. 2000 (Z1-4), for embryo selection is assessed.
  
  
  RESULTS
  Sinchrony on polarization and number of nucleolar precursor bodies (NPB) were associated with good quality embryos (p0 60.9% and p3 67.3%, and Z1 62.5% and Z2 64.7%; p<0.01). Pattern 4 zygotes were associated with small number of NPB developed into multinucleated embryos (14.3%) and poor quality embryos (61.9%). No significant differences were found in the pregnancy rate between transfer of at least one good prognosis PN pattern and transfer of poor prognosis PN patterns, although 75% of the transfers included at least one embryo derived from a pattern 0 zygote, and 55% included embryos from categories Z1 or Z2.
  
  
  CONCLUSIONS
  Sequential assessment involving the evaluation of oocyte quality, the classification of PN patterns and embryo morphology allows a more accurate evaluation of embryos to be selected for transfer.
authors.affiliation: Servei Medecina de la Reproducció, Dpt Obstetrícia i Ginecologia, Institut Universitari Dexeus, Passeig Bonanova, Barcelona, Spain. gemarr@dexeus.com
authors.forename: Gemma
authors.initials: G
authors.lastname: Arroyo
authors.forename: Anna
authors.initials: A
authors.lastname: Veiga
authors.forename: Josep
authors.initials: J
authors.lastname: Santaló
authors.forename: Pere Nolasc
authors.initials: PN
authors.lastname: Barri
mesh_terms: D002467:Cell Nucleus / Q000502:physiology*; D016764:Cell Polarity; D003593:Cytoplasm / Q000648:ultrastructure; D019924:Embryo Disposition; D005260:Female; D006801:Humans; D010062:Ovulation Induction; D011247:Pregnancy; D011379:Prognosis; D014617:Vacuoles / Q000648:ultrastructure; D015053:Zygote / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure