Immunolabeling of 0.5-μm-thin retinal sections from wild-type mice (A–C) and Tulp1 knock-out mice (D–F) of the indicated ages immunolabeled with antibodies against RIBEYE. Images are conventional epifluorescence images. Four experiments from four animals of each genotype (littermates). Abbreviations: OLM, Outer limiting membrane; ONL, outer nuclear layer. Scale bars, A–F, 5 μm. G, H, SR-SIM images of photoreceptor ribbons from P16-d-old wild-type (G) and Tulp1 knock-out mice (H). OLM, Outer limiting membrane; ONL, outer nuclear layer; OPL, outer plexiform layer. Scale bars, G, H, 1 μm. I, Quantification of photoreceptor synaptic ribbon numbers. ***p < 0.001. Error bars indicate SD.