Fig. 2. Gli3 is required for proper establishment of the inferior colliculus. (A-D) En1 RNA expression in the E18.5 inferior colliculus (Ic) and posterior superior colliculus (Sc) in sagittal sections from WT mouse (A). En1 expression is severely reduced in Gli3^-/- mutants, slightly reduced in En1-Gli3 cko and normal in Nes-Gli3 cko mutants (B-D). (E-H) Expression of Otx2 RNA in superficial layers of the Sc and in the ventricular layer of the Ic is comparable in WT (E) and Nes-Gli3 cko brains (H). In Gli3^-/- and En1-Gli3 cko mutants, Otx2 is expressed throughout the posterior tectum and the thickness of the Otx2-positive layer is increased in the Sc (F,G). (I,J) Immunohistochemistry for neurogranin on E18.5 sagittal sections. The neurogranin-positive domain (outlined in red) is reduced and shifted posteriorly in Gli3^-/- mutants. (K-N) DAPI staining (K) and immunohistochemistry for neurogranin (L-N) at P16 show that the Ic is abnormally shaped in En1-Gli3 cko, but not in Nes-Gli3 cko mutants. Scale bars: 250 µm in A-H,I,J,L-N; 500 µm in K.