Characterization of Otx2OG/OGhomozygous embryos. a. Morphology of Otx2OG/OGand control Otx2+/OGanimals at E8.5. b. Analysis of Otx2-GFP and brain markers in Otx2OG/OGand control Otx2+/OGE9.5 embryos. Otx2-GFP is seen by direct GFP fluorescence visualisation and Six3, En2, Gbx2 and Fgf8 mRNAs are detected by whole-mount in situ hybridization. For E9.5 Otx2OG/OGanimals, upper and lower panels show embryos with weak and strong abnormalities respectively. Anterior is leftward. Scale bar: 500 μm. c. Detection of Otx2, Otx2-GFP and Otx1 proteins by western blot analysis of nuclear extracts from tails and heads of Otx2+/+and Otx2+/OGE9.5 embryos using an anti-Otx antibody. d. Normal structure of the retina in surviving Otx2OG/OGadults. Comparison of bright field (BF left panels), GFP fluorescence (middle panels) and GFAP expression (right panels) in adult retinas of the indicated genotype. Scale bars : 50 μm.