title: Zona pellucida birefringence in in vivo and in vitro matured oocytes.
abstract: OBJECTIVE
  To evaluate zona pellucida birefringence (ZPB) in immature and mature oocytes collected after controlled ovarian stimulation and to assess the influence of ZPB on oocyte development.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Private assisted reproduction centre.
  
  
  METHODS
  Thirty patients undergoing intracytoplasmic sperm injection.
  
  
  METHODS
  The ZPB of mature and immature oocytes was evaluated using a polarization imaging software module, and the oocytes were classified as high birefringence (HB) or low birefringence.
  
  
  METHODS
  The ZPB of in vivo and in vitro matured oocytes and its influence on spontaneous nuclear maturation in vitro, fertilization, and embryo quality.
  
  
  RESULTS
  The percentage of HB oocytes was higher in immature than in mature oocytes (40.1 vs. 23.6%). Among immature oocytes, an increased percentage of HB in prophase-I stage oocytes compared to metaphase I stage oocytes was also observed (50.7 vs. 25.0%). However, the percentage of HB oocytes did not change when comparing oocytes before and after in vitro maturation for both prophase I and metaphase I oocytes. No influence of ZPB was observed on the spontaneous in vitro maturation potential. Exclusively for metaphase II retrieved oocytes, a positive influence of ZPB on fertilization (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.27-2.49) and embryo quality (OR, 2.28; 95% CI, 1.04-4.99) was noted.
  
  
  CONCLUSIONS
  ZPB may be a useful tool to predict embryo quality for metaphase-II oocytes. Moreover, the completion of nuclear changes in the production of metaphase-II oocytes in vitro may not reflect their molecular maturity.
authors.affiliation: Fertility-Assisted Fertilization Center, São Paulo, Brazil.
authors.forename: Daniela Paes
authors.initials: DP
authors.lastname: de Almeida Ferreira Braga
authors.forename: Rita
authors.initials: R
authors.lastname: de Cássia Savio Figueira
authors.forename: Priscila
authors.initials: P
authors.lastname: Queiroz
authors.forename: Camila
authors.initials: C
authors.lastname: Madaschi
authors.forename: Assumpto
authors.initials: A
authors.lastname: Iaconelli
authors.forename: Edson
authors.initials: E
authors.lastname: Borges
mesh_terms: D001718:Birefringence; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D004624:Embryo Transfer; D005260:Female; D005306:Fertilization / Q000502:physiology; D006801:Humans; D009865:Oocytes / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D009866:Oogenesis / Q000502:physiology*; D010062:Ovulation Induction; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic; D015044:Zona Pellucida / Q000737:chemistry / Q000502:physiology*