Fig. 3. Expression of Ptgds in embryonic gonads. Whole-mount in situ hybridisation for Ptgds was performed on isolated 11.5 dpc (A,B), 12.5 dpc (C) or 13.5 dpc (D) male and female urogenital ridges, as indicated. W^e/W^e testes (14.5 dpc) were used in (E). At 11.5 dpc, paired urogenital ridges with intervening mesenchyme are shown with the genital ridges lying on top of the mesonephroi along the left and right edges of the tissue. At 12.5-14.5 dpc, single urogenital ridges are shown, orientated with the mesonephros on the left and the genital ridge on the right. Sections of 13.5 dpc male urogenital ridges after whole-mount in situ hybridisation for Ptgds are shown in (F). Sertoli cells are marked with arrowheads, prospermatogonia with arrows. Sections are stained with neutral red to show the nuclei. Transcript expression is visualised by a dark blue/purple precipitate. Scale bars: in E, 200 mm in A-E; in F, 10 µm.