The effect of temperature on the motility and viability of sperm

Br J Urol. 1977;49(7):751-6. doi: 10.1111/j.1464-410x.1977.tb04566.x.


In specimens of semen kept at 37 degrees C sperm lose their motility and viability. If kept at 4 degrees C they retain their viability but lose their motility from so-called thermal shock. The best temperature to keep semen in order to preserve sperm motility is 20 degrees C. Loss of motility at 37 degrees C is not entirely prevented by prevention of bacterial contamination with antibiotics.

PIP: Semen specimens were obtained from 42 fertile men requesting voluntary vasectomy and stored at 4, 20, and 37 degrees C. Analysis of motility, viability under oil immersion, and pH was made after 3, 6, 12, and 18 hours. When semen was kept at 20 degrees C there was negligible deterioration in motility after 12 hours. However, there was a significant (p .01) decrease in motility in semen kept at 4 or 37 degrees, the worst being at 4 degrees. In these experiments mortility could not be restored by rewarming the semen. Viability followed motility closely at 20 and 37 degrees but at 4 degrees C viability was well preserved despite loss of motility. At the higher temperatures the motionless sperms were dead but this was not the case at 4 degrees. As expected, there was more bacterial growth at higher temperatures, mainly gram-negative bacteria such as Esch. coli and Proteus although an occasional gram positive Enterococci were identified. At 37 degrees the semen became significantly acidic (p .001). To determine the effect of bacterial growth on sperm motility, the experiment was repeated with antibiotics added. None grew any organisms and there was no fall in pH, even at 37 degrees C. Sperm kept in the presence of antibiotics retained motility at 20 and 37 degrees C better than those kept without antibiotics but there was still a significant deterioration (p .01) in the samples kept at body temperature even when bacterial growth was prevented. These studies show it is better to keep a sample of semen at room temperature (20 degrees C) during the time between ejaculation and semen analysis but do not fully explain why this is so. Specimens kept at 37 degrees C lose both motility and viability. Those kept at 4 degrees lose motility from so-called thermal shock but retain viability.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Cell Survival / drug effects
  • Humans
  • Hydrogen-Ion Concentration
  • Male
  • Semen / drug effects
  • Semen / microbiology
  • Semen Preservation
  • Sperm Motility* / drug effects
  • Spermatozoa / cytology*
  • Spermatozoa / drug effects
  • Temperature*


  • Anti-Bacterial Agents