title: 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?
abstract: 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.
authors.affiliation: Department of Animal Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Ishihara
authors.forename: Seiichiroh
authors.initials: S
authors.lastname: Ohsako
authors.forename: Ken
authors.initials: K
authors.lastname: Tasaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Harayama
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyake
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Warita
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanida
authors.forename: Tomoko
authors.initials: T
authors.lastname: Mitsuhashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nanmori
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hoshi
mesh_terms: D000818:Animals; D004822:Epididymis / Q000166:cytology; D005260:Female; D005298:Fertility; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018812:Paternal Exposure / Q000009:adverse effects*; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage* / Q000633:toxicity*; D011247:Pregnancy; D012744:Sex Ratio; D013076:Sperm Count / Q000662:veterinary; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000502:physiology
chemical_list: D000072317:Polychlorinated Dibenzodioxins