title: In vitro development and chromosome constitution of embryos derived from monopronucleated zygotes after intracytoplasmic sperm injection.
abstract: OBJECTIVE
  To study the chromosome constitution and in vitro development of embryos derived from monopronucleated (1PN) zygotes after intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Private assisted reproduction center.
  
  
  METHODS
  Fifty-four 1PN 2PB zygotes obtained from 48 ICSI cycles.
  
  
  METHODS
  Pronuclear diameter measured 18 ± 2 hours after ICSI and embryonic in vitro development assessed until the blastocyst stage or arrest; embryos disaggregated and all cells analyzed for chromosomes 13, 18, 21, X, and Y by fluorescent in situ hybridization (FISH).
  
  
  METHODS
  Pronuclear size, in vitro embryo development, and cytogenetic characteristics.
  
  
  RESULTS
  All the embryos were chromosomally abnormal (7.4% diploid mosaic, 16.7% haploid mosaics, 5.5% aneuploid mosaic, and 70.4% chaotic mosaic), and 35.2% showed a Y chromosome. No difference in the pronuclear size was observed according to the type of abnormality. Only 7.4% of the embryos resulted in blastocysts with good morphologic features.
  
  
  CONCLUSIONS
  Despite showing only one pronucleus, most of the zygotes resulted from fertilization. Embryos derived from 1PN ICSI zygotes are chromosomally abnormal. Neither the pronuclear size nor the in vitro developmental ability of these embryos can be predictive of their chromosomal constitution. According to our results, embryos that develop from 1PN ICSI zygotes should be discarded for any reproductive purpose.
authors.affiliation: Reproductive Medicine Service, Department of Obstetrics, Gynecology and Reproduction, Institut Universitari Dexeus, Barcelona, Spain. silmat@dexeus.com
authors.forename: Sílvia
authors.initials: S
authors.lastname: Mateo
authors.forename: Mònica
authors.initials: M
authors.lastname: Parriego
authors.forename: Montserrat
authors.initials: M
authors.lastname: Boada
authors.forename: Francesca
authors.initials: F
authors.lastname: Vidal
authors.forename: Buenaventura
authors.initials: B
authors.lastname: Coroleu
authors.forename: Anna
authors.initials: A
authors.lastname: Veiga
mesh_terms: D002869:Chromosome Aberrations; D015925:Cryopreservation; D046149:Embryo Culture Techniques; D047108:Embryonic Development / Q000235:genetics* / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000592:standards; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods* / Q000592:standards*; D011446:Prospective Studies; D011786:Quality Control; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods / Q000592:standards*; D015053:Zygote / Q000473:pathology* / Q000502:physiology