A quantitative investigation of gonadal feminization by diethylstilboestrol of genetically male embryos of the quail Coturnix coturnix japonica.

The effect of diethylstilboestrol on gonad development in quail embryos has been quantitatively analysed. Quail embryos at 4 days of incubation were treated with diethylstilboestrol (DES), using the egg dipping method. At 10 days of incubation, embryos were removed and killed by decapitation. Tissues were prepared for chromosome analysis, and the parts of the abdomen containing the gonads were prepared for serial sectioning and quantitative assessment. Left gonads of DES-treated male embryos resembled ovaries histologically, while their right gonads were markedly reduced in size. Right gonads of DES-treated female embryos were also further reduced by treatment with DES. There was no statistically significant effect by DES treatment on the size of left gonads, although the ratio of left compared with right gonadal volumes was highly significant. Since, in birds, the left embryonic gonad has ambisexual potential, while the potential of the right gonad is exclusively masculine, these results exemplify the adverse effect exerted by oestrogen on male sexual development in vertebrates.