Figure 2. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in the neuroretina. TUNEL staining of retinal sections from pigs subject to retinal ischemia followed by 5, 12, or 20 h of reperfusion versus control (sham). Note that TUNEL-positive cells can be detected in retinas from ischemia-reperfusion eyes but are absent in retinas from sham-operated eyes. The number of TUNEL-labeled cells increases gradually with the duration of reperfusion. TUNEL-positive cells are observed throughout the retinal sections, including the outer nuclear layer (ONL), inner nuclear layer (INL), and ganglion cell layer (GCL). The bottom panels are enlargements of the inserts above.