Fig. 1.

Expression of Nrl in cone precursors. (A–L) Toluidine blue stainings of WT (A), Crxp-Nrl/WT (B), Nrl^−/− (C), and Crxp-Nrl/Nrl^−/− (D) retinal sections demonstrate unique chromatin pattern in the photoreceptor layer for cones (indicated by arrowhead) and rods. Normal laminar structure is observed in both Crxp-Nrl/WT (B) and Crxp-Nrl/Nrl^−/− (D) plastic sections. Immunohistochemical markers for rod photoreceptors (rhodopsin) can be detected in WT (E), Crxp-Nrl/WT (F), and Crxp-Nrl/Nrl^−/− (H) retina but not in Nrl^−/− (G). The pan cone photoreceptor marker, cone arrestin, is present only in WT (I) and Nrl^−/− (K) retina, but is largely absent in the Crxp-Nrl/WT (J) and Crxp-Nrl/Nrl^−/− (L). (M–P) ERG intensity series and responses were recorded from 2-mo-old WT, Nrl^−/−, Crxp-Nrl/WT, and Crxp-Nrl/Nrl^−/− mice under dark- (scotopic ERG; M and N) and light-adapted (photopic ERG; O and P) conditions. The x axes for M and O indicate time lapsed after flash. Stimulus energy is indicated (log cd-s/m²). OS, outer segments; IS, inner segments, ONL, outer nuclear layer; INL, inner nuclear layer. (Scale bars: A–D, 25 μm; E–L, 50 μm.)