title: Prevalence of tetraploid metaphases in semidirect and cultured chorionic villi.
abstract: OBJECTIVE
  Investigation of the normal frequency of tetraploid metaphases in semidirect (STC) and cultured (LTC) chorionic villi.
  
  
  METHODS
  Fifty metaphases in STC- and in LTC-villi slides of 100 women of advanced maternal age were screened for tetraploidy.
  
  
  RESULTS
  Up to three tetraploid metaphases were encountered in 27% of the STC-villi preparations; the scores fitted a Poisson distribution. In all LTC-villi preparations tetraploid cells were seen; the scores fitted a log-Gaussian distribution.
  
  
  CONCLUSIONS
  On the basis of these distributions, we propose a protocol for the management of tetraploid metaphases in chorionic villi, strongly reducing the number of prenatal follow-up investigations.
authors.affiliation: Department of Clinical Genetics, University Hospital Dijkzigt, Erasmus University Rotterdam, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Noomen
authors.forename: C
authors.initials: C
authors.lastname: van den Berg
authors.forename: J L
authors.initials: JL
authors.lastname: de Ruyter
authors.forename: D
authors.initials: D
authors.lastname: Van Opstal
authors.forename: F J
authors.initials: FJ
authors.lastname: Los
mesh_terms: D002478:Cells, Cultured; D002824:Chorionic Villi / Q000473:pathology*; D015193:Chorionic Villi Sampling / Q000706:statistics & numerical data*; D002869:Chromosome Aberrations / Q000453:epidemiology*; D025063:Chromosome Disorders; D005260:Female; D006801:Humans; D009030:Mosaicism / Q000473:pathology*; D016012:Poisson Distribution; D011123:Polyploidy; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D015995:Prevalence; D012016:Reference Values