Transmission electron micrographs of the outer retina of SD (A and D), S334ter-4 (B and E) and P23H-3 (C and F) at the age of P21. The upper row is at low magnification and the lower row is at higher magnification. In the S334ter-4 retina, many small extracellular vesicles (arrows) are present in the interphotoreceptor space (IPS) in the basal region of the OSs (OS) and apical region of the ISs (IS). These are absent in the SD (A and D) and P23H-3 (C and F) retinas. cc, connecting cilium; RPE, retinal pigment epithelium. Magnification bars = 5 μm in AC; 2 μm in D–F, with E at a slightly higher magnification than A and F.