When does the sex ratio of offspring of the paternal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure decrease: in the spermatozoa stage or at fertilization?

Reprod Toxicol. 2010 Jan;29(1):68-73. doi: 10.1016/j.reprotox.2009.09.009. Epub 2009 Oct 4.


Recent animal experiments confirmed that paternal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure decreases the sex ratio of offspring at birth without altering litter size. However, the timing of this decrease remained unclear. Male mice were administered TCDD at 7-12 weeks of age and mated with non-treated females. The Y-bearing/X-bearing sperm ratio was examined by real-time PCR and FISH methods, and the sex ratio of the 2-cell embryos collected from non-treated females that had been mated with TCDD-exposed males were investigated by nested PCR. The Y-bearing/X-bearing sperm ratio was not significantly decreased in the TCDD group. However, the sex ratio of the 2-cell embryos of the TCDD group was significantly lower than that of the control group. These results may have resulted from a decrease in fertility of Y-bearing sperm. Thus, the results of this study suggested that the sex ratio of the offspring was decreased at fertilization and not during the spermatozoa stage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Epididymis / cytology
  • Female
  • Fertility
  • Male
  • Mice
  • Mice, Inbred ICR
  • Paternal Exposure / adverse effects*
  • Polychlorinated Dibenzodioxins / administration & dosage*
  • Polychlorinated Dibenzodioxins / toxicity*
  • Pregnancy
  • Sex Ratio*
  • Sperm Count / veterinary
  • Sperm Motility / drug effects
  • Spermatozoa / chemistry
  • Spermatozoa / cytology
  • Spermatozoa / drug effects
  • Spermatozoa / physiology


  • Polychlorinated Dibenzodioxins