title: High magnitude of light retardation by the zona pellucida is associated with conception cycles.
abstract: BACKGROUND
  Failures in expression of zona proteins correlate to subfertility in animals. Low expression of the zona proteins by the growing human oocyte may indicate reduced developmental potential. Therefore, we non-invasively analysed the thickness and the structure of the zona pellucida (ZP) of human oocytes with respect to embryo fate after ICSI.
  
  
  METHODS
  Retardance magnitude and thickness of the inner, middle and outer layers of the ZP were quantitatively analysed by a Polscope in 166 oocytes selected for transfer after ICSI (63 patients; 32.8 +/- 4.4 years) on the basis of pronuclear score at day 1. Blastomere number was determined at day 2. Data were compared between conception cycles (CC; 65 oocytes/23 patients) and non-conception cycles (NCC; 101 oocytes/40 patients) and with respect to maternal age.
  
  
  RESULTS
  The thickness was slightly elevated (P < 0.001), and the mean magnitude of light retardance was nearly 30% higher (P < 0.001) in the inner layer of the zona pellucida of oocytes contributing to CC compared to NCC. Embryos in the CC group tended to develop faster.
  
  
  CONCLUSIONS
  The magnitude of light retardance by the zona pellucida inner layer appears to present a unique non-invasive marker for oocyte developmental potential.
authors.affiliation: Centre of In-Vitro-Fertilisation (CIF) in Justus-Liebig-University, D-35392 Giessen, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Shen
authors.forename: T
authors.initials: T
authors.lastname: Stalf
authors.forename: C
authors.initials: C
authors.lastname: Mehnert
authors.forename: U
authors.initials: U
authors.lastname: Eichenlaub-Ritter
authors.forename: H-R
authors.initials: HR
authors.lastname: Tinneberg
mesh_terms: D000328:Adult; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008027:Light; D008423:Maternal Age; D008853:Microscopy / Q000379:methods; D009865:Oocytes / Q000502:physiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic; D016896:Treatment Outcome; D015044:Zona Pellucida / Q000648:ultrastructure*