Figure 1. Establishment of a mouse retina–retinal pigment epithelium (RPE) explant system. A: The bright-field micrograph of a C57BL/6 mouse retinal explant placed in culture at postnatal day 7 (P7; which is called days in vitro 0, DIV0) and analyzed at DIV11 (P18=P7+11DIV) shows that normal retinal layers are formed and maintained in situ. B: A P18 C57BL/6 mouse retina is provided for comparison. In culture, rhodopsin (C), ultraviolet (UV) opsin (E), middle-wavelength (MWL) opsin (F), and cone transducin (G) are trafficked properly to the photoreceptor outer segment. H: Cone arrestin is present in the inner segments and cone pedicles, as described for light-adapted retinas [30]; a double labeling (inset of panel H) of cone arrestin with PNA-lectin is provided to allow for visualization of inner and outer segments. D: No-primary antibody control is provided for nonspecific staining of the secondary antibodies. Images are representative examples from three to five different litters. Abbreviations: GCL, ganglion cell layer; INL, inner nuclear layer; IPL, inner plexiform layer; IS, inner segments; ONL, outer nuclear layer; OPL, outer plexiform layer; OS, outer segments. Scale bar 50 μm.