title: Prospective, auto-controlled study on reinsemination of failed-fertilized oocytes by intracytoplasmic sperm injection.
abstract: OBJECTIVE
  To evaluate the possible influence of late fertilization after standard IVF on the results of reinsemination of assumed failed-fertilized oocytes by microinjection and to examine the correlation between the effect of aging of (failed-fertilized) oocytes and the ability of these oocytes to become fertilized.
  
  
  METHODS
  Trial 1: Group 1 (injected-day 1), 93 failed-fertilized oocytes injected 1 day after ovum pick-up; group 2 (control), 82 failed-fertilized oocytes with no microinjection performed. Trial 2: Group 1 (ICSI-day 1), 40 failed-fertilized oocytes injected 1 day after ovum pick-up; group-2 (ICSI-day 2), 40 failed-fertilized oocytes injected 2 days after ovum pick-up. In addition, 35 two- to eight-cell stage embryos, obtained after ICSI of IVF failed-fertilized oocytes, were fixed for cytogenetic analysis.
  
  
  METHODS
  Normal and abnormal fertilization and embryo development.
  
  
  RESULTS
  Trial 1: 53% normal (2 pronuclear [PN]) and 25% abnormal (> or = 3PN) fertilization rates were obtained in group 1 (injected-day 1), and 71% of the 2PN and 74% of the > or = 3PN oocytes cleaved with < 50% fragmentation. No pronuclear (> or = 2PN) development occurred in the control group. Trial 2: 45% and 8% normal and 25% and 40% abnormal fertilization rates were obtained, respectively, after ICSI of 1-day-old and 2-day-old failed-fertilized oocytes. Two days after microinjection, 67% and 67% of the 2PN and 80% and 44% of the > or = 3PN oocytes cleaved with < 50% fragmentation in group ICSI-day 1 and in group ICSI-day 2, respectively.
  
  
  CONCLUSIONS
  Late fertilization after initial in vitro insemination does not play a role in the high fertilization rate obtained after reinsemination of assumed failed-fertilized oocytes by ICSI. Normal (2PN) fertilization rate, however, decreases strongly and the abnormal (> or = 3PN) fertilization rate increases with oocyte aging and derived embryos seem to have a high incidence of cytogenetic abnormalities.
authors.affiliation: Centre for Reproductive Medicine, University Hospital, Dutch-speaking Brussels Free University (Vrije Universiteit Brussel), Belgium.
authors.forename: Z P
authors.initials: ZP
authors.lastname: Nagy
authors.forename: C
authors.initials: C
authors.lastname: Staessen
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: H
authors.initials: H
authors.lastname: Joris
authors.forename: P
authors.initials: P
authors.lastname: Devroey
authors.forename: A C
authors.initials: AC
authors.lastname: Van Steirteghem
mesh_terms: D002467:Cell Nucleus / Q000648:ultrastructure; D016922:Cellular Senescence; D002869:Chromosome Aberrations; D002970:Cleavage Stage, Ovum; D003593:Cytoplasm; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007621:Karyotyping; D008297:Male; D008845:Microinjections; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D011446:Prospective Studies; D013094:Spermatozoa