title: Analysis of the human zona pellucida during culture: correlation with diagnosis and the preovulatory hormonal environment.
abstract: OBJECTIVE
  The objective of this study was to analyze sequentially the human zona pellucida changes in an in vitro fertilization program as it relates to several variables.
  
  
  METHODS
  The zona pellucida thickness was measured daily in zygotes and cleavage-stage embryos on a Nikon inverted microscope equipped with Hoffman modulation contrast optics, using an ocular micrometer. A total of 512 embryos from 96 patients was evaluated.
  
  
  RESULTS
  There was a highly significant direct correlation between zona thickness and preovulatory estradiol and basal day 3 FSH levels (P < 0.02 and P < 0.0006, respectively). This relationship showed a rapid reversal following 48 hr of culture; embryos from patients with the highest FSH levels had thinner zonae prior to transfer (P < 0.0007). The zonae from patients with unexplained infertility were thicker (19.4 +/- 2.7 microns) than those from patients with endometriosis (17.7 +/- 2.2 microns), tubal (17.5 +/- 2.4 microns), or male-factor infertility (16.4 +/- 2.7 microns) (P < 0.0001) on the first day of culture.
  
  
  CONCLUSIONS
  We hypothesize that the thickness of the human zona pellucida is influenced by the preovulatory hormonal environment and diagnosis. These factors should be considered as part of the embryo quality evaluation prior to transfer or when assessing the possibility of using assisted hatching. More studies are needed to understand the factors regulating the thickness of the human zona pellucida.
authors.affiliation: Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Loret De Mola
authors.forename: W T
authors.initials: WT
authors.lastname: Garside
authors.forename: J
authors.initials: J
authors.lastname: Bucci
authors.forename: R W
authors.initials: RW
authors.lastname: Tureck
authors.forename: S
authors.initials: S
authors.lastname: Heyner
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000648:ultrastructure*; D002478:Cells, Cultured; D004624:Embryo Transfer; D004958:Estradiol / Q000097:blood*; D005260:Female; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000097:blood*; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000628:therapy; D007248:Infertility, Male; D008297:Male; D015588:Observer Variation; D010060:Ovulation / Q000097:blood*; D011247:Pregnancy; D018873:Pregnancy Rate; D015044:Zona Pellucida / Q000648:ultrastructure*; D015053:Zygote / Q000648:ultrastructure*
chemical_list: D004958:Estradiol; D005640:Follicle Stimulating Hormone