title: Fertilization, cleavage, and cytogenetics of 48-hour zona-intact and zona-free human unfertilized oocytes reinseminated with donor sperm.
abstract: OBJECTIVE
  To examine the fertilization rates of 48-hour unfertilized oocytes inseminated with fertile donor sperm and to evaluate the cleavage and cytogenetics of ensuing embryos.
  
  
  METHODS
  Prospective.
  
  
  METHODS
  Assisted reproductive technology (ART) program.
  
  
  METHODS
  Four hundred ninety-seven unfertilized oocytes from 97 ART patients were categorized into four groups. A (zona-intact) and B (zona-free) were from patients with partial fertilization failure, whereas C (zona-intact) and D (zona-free) were total fertilization failures.
  
  
  RESULTS
  Fertilization rates in groups A and B were significantly higher than C and D (33.2% to 60.9% versus 20.0% to 48.1%; P less than 0.01). Zona-free oocytes had higher fertilization rates than zona-intact oocytes (48.1% to 60.9% versus 20.0% to 32.2%). Multiple pronuclei were high in zona-free oocytes (33.1% to 41.3%). Forty-eight to 54% of embryos generated after donor insemination had chromosome anomalies (mosaicism, aneuploidy, pulverization).
  
  
  CONCLUSIONS
  One cause of total fertilization failure appears to lie in intrinsic oocyte problems confined to the zona and oolemma. The fertilization of 48-hour unfertilized oocytes may be of some value in diagnosing fertilization failure in ART patients.
authors.affiliation: Department of Obstetrics and Gynaecology National University of Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Bongso
authors.forename: C Y
authors.initials: CY
authors.lastname: Fong
authors.forename: S C
authors.initials: SC
authors.lastname: Ng
authors.forename: S
authors.initials: S
authors.lastname: Ratnam
mesh_terms: D002455:Cell Division; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D011446:Prospective Studies; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions; D015044:Zona Pellucida / Q000502:physiology