Figure 3. Light-induced damage caused Zn²⁺ accumulation preferentially in superior photoreceptors, retinal pigment epithelial (RPE), rod outer segments (ROS), and outer plexiform layer (OPL). Light-induced damage (LD) was performed and fresh frozen rat retinas were analyzed at 4 or 14 h after 1 h of light damage in dark maintained conditions (dark) or after 4 h of light damage in non-dark maintained conditions (light). Zn²⁺ accumulation (white regions) was assessed by ZP1 staining of fresh frozen rat eye cryostat sections cut at 10 microns, which were dried and stained in 5 μM ZP1 for 2 min. Representative photomicrographs (n=4) were taken of the mid inferior and mid superior regions of the retina at 5 s exposure for: control, 4 h LD (light) + 4 h, and 1 h LD (dark) + 4 h; at 1 s exposure for: 1 h LD (dark) + 14 h; and at 2 s exposure for: 4 h LD (light) + 14 h, and 1 h LD (light) + 14 h. Layers are as marked. Notice the large increase in the number and intensity of Zn²⁺ stained cells in superior ONL (brackets), ROS, and RPE. Light=non-dark maintained, Dark=dark maintained.