title: Selective microsurgical removal of a pronucleus from tripronuclear human oocytes to restore diploidy: disregarded but valuable?
abstract: OBJECTIVE
  To review data on the microsurgical removal of a single pronucleus from tripronuclear human oocytes and evaluate the future potential of this technique for obtaining diploid, transferable embryos.
  
  
  METHODS
  Literature review.
  
  
  METHODS
  None.
  
  
  METHODS
  None.
  
  
  METHODS
  None.
  
  
  METHODS
  None.
  
  
  RESULTS
  Ten relevant studies were identified. These differ considering the removal technique itself, the application of cytoskeletal relaxants, and the survival rate after epronucleation. Diploidy and heteroparental inheritances could be confirmed in some preimplantation stages derived from epronucleated oocytes. Transfer of "corrected" embryos has been attempted only once, and resulted in a live birth. Noteworthy pitfalls associated with the procedure concern the exact identification of the supernumerary pronucleus, the presence of two centrosomes in dispermic oocytes, and cytogenetically abnormal pronuclear patterns after intracytoplasmic sperm injection.
  
  
  CONCLUSIONS
  Patients with exclusively abnormally or few normally fertilized oocytes would profit from epronucleation to assure embryo transfer or increase the number of transferable embryos. Further research appears necessary and promising.
authors.affiliation: Department of Gynecology and Obstetrics, University of Ulm, Ulm, Germany. Electronic address: bernd.rosenbusch@uniklinik-ulm.de.
authors.forename: Bernd E
authors.initials: BE
authors.lastname: Rosenbusch
mesh_terms: D002467:Cell Nucleus; D018385:Centrosome; D004171:Diploidy; D004624:Embryo Transfer / Q000379:methods; D005260:Female; D005307:Fertilization in Vitro / Q000331:legislation & jurisprudence / Q000379:methods; D006801:Humans; D008297:Male; D008866:Microsurgery / Q000379:methods*; D020554:Sperm Injections, Intracytoplasmic / Q000331:legislation & jurisprudence / Q000379:methods