Fig. 8. Altered Chx10 and Crx homeobox gene expression in the E18.5 Dlx1/Dlx2 mutant retina. (A) Combined CHX10 immunohistochemistry with Crx digoxigenin in-situ hybridization in wild-type retina. CHX10 (brown stain) is localized primarily in the outer retina throughout the NBL. Crx RNA expression (blue stain) can be found in the extreme outer retina. (B) In the Dlx1/Dlx2 mutant there is increased Crx expression in the outer retina as well as ectopic expression in the central retina (arrows) and GCL (box, insert). Note the reduced GCL (double-headed arrows). (C) Crx in-situ hybridization of E18.5 wild-type retina. (D) Crx in-situ hybridization of E18.5 Dlx1/Dlx2 null retina. Ectopic Crx expression is clearly identified in the GCL of the mutant (D, box). Scale bars: 40 µm. Inserts in B,D represent a 3-fold enlargement.