title: Enhanced separation of X and Y bearing sperm cells by a combined density gradient centrifugation evaluated by fluorescence in situ hybridization of the Y-chromosome.
abstract: OBJECTIVE
  Fluorescent in situ hybridization of decondensed sperm cells was used to evaluate the effectiveness of separating X- and Y chromosome bearing sperm cells using a combination of Percoll and NycoPrep media.
  
  
  METHODS
  Semen samples from seven healthy men were divided into three equal aliquots. One aliquot served as an untreated control, the other two were either applied to a seven-step Percoll gradient (100%-40%), or to a seven-step Percoll gradient (100%-40%) underlayered with 100% NycoPrep for sperm purification. After centrifugation Y-bearing sperm cells in the pellet and in the control sample was determined by fluorescent in situ hybridization.
  
  
  RESULTS
  A significantly reduction of Y-bearing sperm cells were observed in the pellet of the Percoll + NycoPrep centrifugation (39.3% Y-bearing sperm cells) compared to the control sample and to Percoll centrifugation without NycoPrep. The Percoll centrifugation without NycoPrep did not show a significant reduction of Y-bearing sperm cells in the pellet compared to the control sample.
  
  
  CONCLUSIONS
  By the addition of a medium with a density higher than 100% Percoll a significantly increased separation of X and Y-bearing sperm cells can be achieved. This study opens new perspectives for improving separation of X- and Y-bearing spermatozoa by simple centrifugations. The described centrifugation technique can be applied in connection with preimplantation diagnosis in order to create more pre-embryos of the desired gender.
authors.affiliation: Laboratory of Reproductive Biology, Women and Reproduction University Hospital of Copenhagen, Denmark.
authors.forename: C Y
authors.initials: CY
authors.lastname: Andersen
authors.forename: A G
authors.initials: AG
authors.lastname: Byskov
mesh_terms: D002469:Cell Separation / Q000379:methods*; D002498:Centrifugation / Q000379:methods*; D003102:Colloids; D003470:Culture Media; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D011205:Povidone; D012016:Reference Values; D012822:Silicon Dioxide; D013076:Sperm Count; D013094:Spermatozoa / Q000166:cytology*; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D003102:Colloids; D003470:Culture Media; C016039:Percoll; D012822:Silicon Dioxide; D011205:Povidone