In ovoexposure too,p0-dichloro-diphenyl-trichloroethane (o,p0-DDT) impairs repro-duction by inducing malformation of the reproductive organs in birds, although themechanism remains unclear. Here, we examined the effects ofo,p0-DDT on thedevelopment of the reproductive organs, the expression of genes controlling sexualdifferentiation, and the plasma concentrations of testosterone and estradiol inJapanese quail embryos.o,p0-DDT-containing sesame oil was injected into the yolksac on Embryonic Day (E) 3 at a dose of 500, 2,000, or 8,000 mu g per egg. On E15, thereproductive organs were observed; the gonads and M & uuml;llerian ducts (MDs) weresampled to measure the mRNA of steroidogenic enzymes, sex steroid receptors, anti-M & uuml;llerian hormone (AMH), and AMH receptor 2 (AMHR2); blood samples were col-lected to assay plasma testosterone and estradiol levels; and the gonads were usedfor histological analysis.o,p0-DDT dose-dependently increased the prevalence ofhypertrophic MDs in females and residual MDs in males. In female MDs,o,p0-DDTdose-dependently decreased estrogen receptor (ER)alpha,ER beta, andAMHR2mRNAexpression.o,p0-DDT dose-dependently induced left-biased asymmetry of testis size,and ovary-like tissue was found in the left testis after exposure to 8,000 mu g per eggo,p0-DDT, although asymmetric gene expression did not occur.o,p0-DDT did notaffect ovarian tissue but did decrease17 alpha-hydroxylase/C17-20 lyasemRNA expres-sion and dose-dependently increasedER beta mRNA expression.o,p0-DDT decreasedplasma testosterone concentrations in females. These findings suggest thato,p0-DDTinduces hypertrophy of the MDs and ovarian tissue formation in the left testis.Abnormal MD development may be linked to altered gene expression for sensingestrogens and AMH signals.
