title: Dynamic aspects concerned with the mechanism of separating motile sperm from nonmotile sperm, leukocytes, and debris with the use of high-density Percoll gradients.
abstract: OBJECTIVE
  To investigate the dynamics and the efficacy of separating motile from nonmotile sperm with the use of Percoll gradients as a function of centrifugation time.
  
  
  METHODS
  In vitro laboratory experiments on human sperm.
  
  
  METHODS
  Male Infertility Institute.
  
  
  METHODS
  Fresh sperm specimens collected from donors and patients.
  
  
  METHODS
  Aliquots of sperm specimens, spread on top of 40% and 80% Percoll layers in test tubes, were centrifuged for 5-60 minutes.
  
  
  METHODS
  After centrifugation, samples were aspirated from the bottom, interface, and top layers for microscopic analysis.
  
  
  RESULTS
  Within 5 minutes, only fast-moving sperm reached the bottom as a result of both centrifugation force and their own tail movements. From 10 minutes onward, nonmotile sperm, slowed down by Percoll, joined them and gradually reversed the separation process. Leukocytes, debris, and abnormal sperm remained in the upper levels and never reached the bottom.
  
  
  CONCLUSIONS
  Separation of motile sperm with the use of Percoll gradients is strongly dependent on centrifugation time. The separation is the gap formed between down-swimming sperm, accelerated by centrifugation, and nonmotile sperm, decelerated by Percoll. This gap gradually disappears with extended spinning.
authors.affiliation: Male Infertility Institute, Department of Obstetrics and Gynecology, Rambam Medical Center and the Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
authors.forename: A
authors.initials: A
authors.lastname: Makler
authors.forename: J
authors.initials: J
authors.lastname: Stoller
authors.forename: E
authors.initials: E
authors.lastname: Makler-Shiran
mesh_terms: D002469:Cell Separation / Q000379:methods*; D002499:Centrifugation, Density Gradient; D003102:Colloids; D006801:Humans; D007248:Infertility, Male / Q000473:pathology*; D007962:Leukocytes / Q000166:cytology*; D008297:Male; D011205:Povidone; D012822:Silicon Dioxide; D013081:Sperm Motility / Q000502:physiology*
chemical_list: D003102:Colloids; C016039:Percoll; D012822:Silicon Dioxide; D011205:Povidone