Fig. 6. Expansion of dorsal gene expression and reduction of Ebf1-positive cells in Nkx2.1^–/–;Gsh2^–/– mice. In situ hybridization and immunohistochemical analysis on coronal sections at E12.5. Ngn2 and Pax6 expression normally extends just across the cortical-striatal sulcus into the dorsal LGE (A,E,M), and CRPB1 expression marks LGE radial glia (I). In Gsh2^–/– mutants, expression of Ngn2 (B) and Pax6 (F,N) expands ventrally into the CRBP1-positive (J,N) mutant LGE. By contrast, in Nkx2.1^–/– mutants, Ngn2 (C) and Pax6 (G,O) expression does not expand into the subpallium, but CRBP1 expression (K,O) expands ventrally into the mutant MGE. Similar to Gsh2^–/– mutants, Nkx2.1^–/–;Gsh2^–/– double mutants display a significant expansion of Ngn2 (D) and Pax6 (H,P) into the ventral-most telencephalon. Arrows show the ventral-most limit of Ngn2 (A-D) and Pax6 (E-H,M-P) expression in control and mutant brains. Similar to Nkx2.1^–/– mutants, CRBP1 expression also expands ventrally Nkx2.1^–/–;Gsh2^–/– double mutants (L,P). Ebf1 is expressed in differentiating cells of the LGE (Q). Ebf1 expression is reduced in the LGE in Gsh2^–/– mutants (R) and expanded ventrally in Nkx2.1^–/– mutants (S). In Nkx2.1^–/–;Gsh2^–/– mutants, Ebf1 expression is both reduced and expanded ventrally (T). Scale bar in A: 200 µm for A-D,Q-T; 100 µm for E-P.