Fig. 6. Delayed Sry expression can induce testis development in XX Wnt4^+/- genital ridges. (A,B) The genital ridges were isolated from the XX Tg Wnt4^+/+ (wild type) or Wnt4^+/- embryos at 18 ts. The left genital ridges were treated with HS (HS+), while the right ones were used as non-treated control (HS-). After culture for 72 hours, sagittal serial sections of these XX Tg explants were comparatively analyzed by anti-SOX9 (A) and anti-laminin (B) staining (brown staining). Both maintenance of SOX9 expression and testis cord formation are properly induced in the XX Wnt4^+/- explant Sry-induced at 18 ts (right upper panels in A,B). In the non-treated (HS-) Wnt4^+/- explant from the same embryo, neither SOX9 expression nor cord formation is detectable (right lower panels in A,B), which is similar to non-treated and Sry-induced XX Tg explants of the Wnt4^+/+ wild-type littermate. Scale bars: 100 µm.