Figure 3. Cone shedding in Nrl^−/− mice shows rhythmic activity in both cyclic light and constant darkness. Phagosome counts were made made every 3 h throughout both the light and dark periods under light-dark (LD) conditions (A) and through subjective light and dark periods under constant darkness (DD) conditions (B). A burst in the number of cone phagosomes was seen at ZT1 (LD) and at circadian time (CT1; total darkness), significantly different from all other values (***p<0.001). Phagosome numbers were lowest in late daytime.