title: Differential production of reactive oxygen species by subsets of human spermatozoa at different stages of maturation.
abstract: BACKGROUND
  Reactive oxygen species (ROS)-mediated damage to human spermatozoa has been implicated in the pathogenesis of male infertility. Although ROS production by human spermatozoa has been extensively studied, the cell-to-cell variation in ROS production by spermatozoa at different stages of maturation has never been investigated.
  
  
  METHODS
  In this study, we determined ROS production by subsets of human spermatozoa at different stages of maturation isolated by density gradient centrifugation of ejaculated spermatozoa obtained from healthy donors and from patients attending a clinic for infertility screening.
  
  
  RESULTS
  Four different fractions were obtained. ROS production was highest in immature spermatozoa with abnormal head morphology and cytoplasmic retention and lowest in mature spermatozoa and immature germ cells (P < 0.01). ROS production was highest in immature spermatozoa from males with abnormal semen parameters compared with donors (P < 0.0001) or patients with normal semen parameters (P = 0.015). ROS production by immature spermatozoa was inversely correlated with the recovery of motile, mature spermatozoa in the high density fraction 4 (P = 0.01).
  
  
  CONCLUSIONS
  The results of this study indicate that there is significant cell-to-cell variation in ROS production in subsets of spermatozoa at different stages of maturation and that oxidative damage of mature spermatozoa by ROS-producing immature spermatozoa during sperm migration from the seminiferous tubules to the epididymis may be an important cause of male infertility.
authors.affiliation: Center for Advanced Research in Human Reproduction and Infertility, Urological Institute, The Cleveland Clinic Foundation, Cleveland, OH 44165, USA.
authors.forename: E
authors.initials: E
authors.lastname: Gil-Guzman
authors.forename: M
authors.initials: M
authors.lastname: Ollero
authors.forename: M C
authors.initials: MC
authors.lastname: Lopez
authors.forename: R K
authors.initials: RK
authors.lastname: Sharma
authors.forename: J G
authors.initials: JG
authors.lastname: Alvarez
authors.forename: A J
authors.initials: AJ
authors.lastname: Thomas
authors.forename: A
authors.initials: A
authors.lastname: Agarwal
mesh_terms: D016922:Cellular Senescence / Q000502:physiology; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013081:Sperm Motility; D013094:Spermatozoa / Q000145:classification* / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D017382:Reactive Oxygen Species