Figure 2. Hematoxylin–eosin and TUNEL staining of SD rat retinas showed progressive changes in the ONL thickness and photoreceptor apoptosis in the in vivo light-induced photoreceptor degeneration model.

(A–E) Compared with the normal group, the photoreceptor number and ONL thickness decreased markedly at different time points after exposure to light (black arrow). (F–I) A few hours after exposure to light, TUNEL-positive cells began to appear in the ONL. (J–K) At 1 day, the number of TUNEL-positive cells reached a peak in the ONL. (L–O) TUNEL-positive cells gradually decreased at 3 and 5 days. (P–Q) At 7 days, TUNEL fluorescence was almost completely absent.