Fig. 2. Desert hedgehog expression in embryonic testes of single and double Sf1 and Dax1 mutants. In situ hybridization of the Sertoli marker Dhh is shown at E11.5 (A-D) and E12.5 (E-H) in genital ridges. The coelomic surface is at the top; anterior is to the left. At E11.5, both Sf1^+/– and Dax1^-/Y single mutants expressed reduced amounts of Dhh (B,C). Expression of Dhh is undetectable in the gonad of the double mutant (D). By E12.5, Dhh expression is comparable in wild-type and single mutant gonads (E-G), and is restored in the double mutant (H). (I-L) Lack of apoptotic death in cells of the E11.5 gonad by TUNEL staining (green) of lateral sections, compared with the Sf1 knock out shown in the inset in I. Arrowhead indicates the coelomic epithelial surface.