Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) indicated that laser injury induced early apoptosis in the outer nuclear layer (ONL) in B6 mice.

<p>TUNEL is a common method for detecting DNA fragmentation that results from apoptotic signaling cascades. No significant morphological disorganization was observed in the retina within hours after laser burns (A, D). Nuclei in ONL exhibited signs of apoptosis about 12 hr after laser injury (B – C) and reached the apoptosis peak by day 3 (E – F, TUNEL-positive nuclei labeling with green fluorescence). The apoptotic and dead cells were indicated by red and white arrowheads, respectively (G – I). Scale bar for images: 100 µm. Abbreviations (the same in the following Figures): B6 mice, C57BL/6 mice; INL, inner nuclear layer; ONL, outer nuclear layer; RPE, retinal pigment epithelium.</p>