Macrophages/microglia activation in the Cyp27a1−/−Cyp46a1−/− retina. Representative staining of the retinal flat mounts for F4/80 (A–D) and retinal cross sections for Iba1 (E and F) and GFAP (G and H). Corresponding images for a Cyp27a1+/+Cyp46a1+/+ mouse (J–Q). I: Histological quantifications. Nuclei were stained with Hoechst (B, D, K, and M) or DAPI (E–H and N–Q). Control sections (Ctrl) were treated with the serum from nonimmunized animals. Scale bar = 100 μm (E–H and N–Q). GCL, ganglion cell layer; INL, inner nuclear layer; IPL, inner plexiform layer; ONL, outer nuclear layer; OPL, outer plexiform layer; RPE, retinal pigment epithelium.