title: Molecular aspects of declining sperm motility in older men.
abstract: OBJECTIVE
  To investigate the molecular mechanism for declining sperm motility in older men.
  
  
  METHODS
  Retrospective and prospective study.
  
  
  METHODS
  University-based andrology unit.
  
  
  METHODS
  Semen was collected from 2,111 patients and sperm donors.
  
  
  METHODS
  None.
  
  
  METHODS
  Age, sperm concentration, ejaculate volume, sperm motility (including velocity average path, velocity straight line, velocity curvilinear, linearity, and lateral head displacement), normal sperm morphology, percentage of abnormally blue-stained flagella, and total and free T, FSH, and LH concentrations were analyzed. In addition, the zinc concentration in the seminal fluid, flagella, and the whole spermatozoa was measured by means of atomic absorption spectrometry.
  
  
  RESULTS
  Patient age correlated negatively with T concentration and sperm motility, including velocity, but positively with the percentage of abnormally stained flagella and the flagellar zinc. Whereas the percentage of abnormally stained flagella correlated negatively with motility and sperm velocity, there was a positive relationship with the flagellar zinc content. Flagellar zinc content was negatively correlated with motility. Testosterone showed a positive relationship with motility and sperm concentration.
  
  
  CONCLUSIONS
  Because the epididymis is functionally T-dependent, our data suggest that the removal of zinc from the outer dense fibers during epididymal sperm maturation is affected in aging men, which in turn will result in decreased sperm motility.
authors.affiliation: Department of Urology, Friedrich Schiller University, Jena, Germany. rhenkel@uwc.ac.za
authors.forename: Ralf
authors.initials: R
authors.lastname: Henkel
authors.forename: Gesa
authors.initials: G
authors.lastname: Maass
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Schuppe
authors.forename: Andreas
authors.initials: A
authors.lastname: Jung
authors.forename: Jörg
authors.initials: J
authors.lastname: Schubert
authors.forename: Wolf-Bernhard
authors.initials: WB
authors.lastname: Schill
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012661:Semen / Q000166:cytology* / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology*; D018709:Statistics, Nonparametric