Figure 4. In situ hybridization in the C57BL/6, BALB/c, 129/Sv, and 129/Sv Cfh^−/− mouse eye. A C57BL/6 eye sectioned near the optic nerve with its negative control (A), RPE65 positive control (B), and Cfh probe (C) are shown. Similar in situ hybridization (ISH) results were observed in the BALB/c strain: negative control (D), RPE65 positive control (E), and Cfh probe (F). Note the robust Cfh mRNA signal in the RPE in both strains (Figure 4C,F). Negative and RPE65 positive controls and Cfh ISH results for a 129/Sv Cfh^−/−mouse (H, J, L) and its background strain, 129/Sv (G, I, K) are shown. To visualize the Fast Red signal masked by the RPE pigment, the Fast Red fluorescence property was used to image the sections using a rhodamine filter for 129/Sv (M) and 129/SvCfh ^−/− (N). Note the greatly reduced signal in the RPE of the Cfh^−/− eye compared to the background strain. RPE=retinal pigment epithelium. Scale bar=20 μm.