Figure 9. Non-random distribution pattern in the time-dependent acquisition of nuclear propidium iodide (PI) fluorescence in ARPE-19 cells exposed to toxic doses of H₂O₂. Live cell imaging of dynamic changes in nuclear PI fluorescence in ARPE-19 cells following pulse delivery of H₂O₂. Images are bright-field-fluorescence overlays from two separate experiments illustrating nuclear PI staining (red) in cells at selected time intervals after exposure to row A: 750 μM or row B: 1000 μM H₂O₂. Images were captured at 5 min intervals after oxidant addition; the acquisition times of the selected images are indicated. The circled area identifies a region where earlier onset nuclear PI fluorescence has begun to fade 5 h later. Scale bar: 40 μm.