title: Human embryo twinning with applications in reproductive medicine.
abstract: OBJECTIVE
  To assess the efficacy of human embryo twinning by blastomere biopsy at different early embryonic stages (splitting efficiency) and to determine the in vitro developmental capacity of twinned human embryos (developmental efficiency).
  
  
  METHODS
  Randomized comparative study.
  
  
  METHODS
  Private IVF centers.
  
  
  METHODS
  Couples undergoing IVF donating triploid embryos.
  
  
  METHODS
  Embryos at the 2- to 5- and 6- to 8-cell stage were split into twin embryos. Half the number of blastomeres from donor embryos were removed and inserted into recipient empty zonae pellucidae. After embryo splitting, donor and recipient embryos were cultured in vitro.
  
  
  METHODS
  Development of twinned embryos to the blastocyst stage.
  
  
  RESULTS
  The number of developing embryos obtained after splitting could be increased in comparison with the number of embryos available before splitting at the 6- to 8-cell stage but not at the 2- to 5-cell stage (splitting efficiency). Splitting of 6- to 8-cell embryos yielded superior rates of twin embryos developing to blastocysts (developmental efficiency). Twinning success was related to the superior morphological quality of embryos used for splitting.
  
  
  CONCLUSIONS
  This is the first report on twinned human embryos developing to blastocysts. This study exhibits the potential for novel applications in human assisted reproduction.
authors.affiliation: American Fertility Services, New York, New York; Genesis Fertility Center, 24 Filopoimenos Street, Patras 26221, Greece. illmensee@genesis.vg
authors.forename: Karl
authors.initials: K
authors.lastname: Illmensee
authors.forename: Mike
authors.initials: M
authors.lastname: Levanduski
authors.forename: Andrea
authors.initials: A
authors.lastname: Vidali
authors.forename: Nabil
authors.initials: N
authors.lastname: Husami
authors.forename: Vasilios T
authors.initials: VT
authors.lastname: Goudas
mesh_terms: D001706:Biopsy; D001755:Blastocyst / Q000166:cytology; D001757:Blastomeres / Q000166:cytology / Q000502:physiology; D002455:Cell Division; D005260:Female; D047109:Fetal Development / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D050498:Live Birth; D008297:Male; D009028:Morula / Q000166:cytology; D011123:Polyploidy; D011247:Pregnancy; D027724:Reproductive Techniques, Assisted / Q000706:statistics & numerical data; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods* / Q000706:statistics & numerical data; D014310:Triplets; D014427:Twins