The distribution of SOX9 protein in oestrogen-treated and control cultures. Immunohistochemistry showing the subcellular distribution of SOX9 in control and oestrogen cultured XY gonads, using AEC+ chromogen red/brown staining (Dako) and counterstained with haematoxylin (blue). In the culture controls (a; magnified in b) localization was nuclear (black arrowhead) and confined to the Sertoli cells of the developing seminiferous cords. In contrast, in the oestrogen-cultured gonads (c; magnified in d), SOX9 was largely cytoplasmic (red arrowheads) and no or very few nuclei were stained. Scale bars are 100 μm in (a) and (b) and 25 μm in (c) and (d).