title: Correlation of scrotal temperature in twins.
abstract: BACKGROUND
  Scrotal temperature and semen quality have been found to be inversely correlated in several studies, and variation in scrotal temperature may contribute to the well known variation in semen quality. The reason for the variation in scrotal temperature is not well understood although determinants could be of a genetic nature.
  
  
  METHODS
  We monitored scrotal skin temperature for 24 h in a group of monozygotic and dizygotic twins and single-born brothers (n = 48 males). A thermistor was attached to the underwear and the temperature of the scrotal skin was recorded every 5 min using a small portable data logger.
  
  
  RESULTS
  A correlation in median scrotal temperature was found among monozygotic twins (r = 0.64, P = 0.01), but not in dizygotic twins and single-born brothers (r = 0.17, NS). Similar results were found for other percentiles of temperature.
  
  
  CONCLUSIONS
  The results suggest a genetic component to the variation in scrotal temperature. An hereditary element in male fecundity may be expressed through scrotal temperature, which constitutes a mechanism independent of those responsible for the development of the sperm producing epithelium.
authors.affiliation: Department of Occupational Medicine, Aarhus University Hospital, Noerrebrogade 44, DK-8000 Aarhus C, Denmark. hhjol@akh.aaa.dk
authors.forename: Niels Henrik I
authors.initials: NH
authors.lastname: Hjollund
authors.forename: Lone
authors.initials: L
authors.lastname: Storgaard
authors.forename: Erik
authors.initials: E
authors.lastname: Ernst
authors.forename: Jens Peter E
authors.initials: JP
authors.lastname: Bonde
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D012611:Scrotum / Q000502:physiology*; D012881:Skin Temperature; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic