Figure 4. Terminal deoxynucleotidyl transferase (TdT)-mediated biotin-dUTP nick-end labeling (TUNEL) analysis in chick lens epithelial cell primary cultures. TUNEL staining to detect DNA fragmentation increased between day 0 (D0) and day 8 (D8) of culture. The histogram shows the mean and SEM of the % of TUNEL positive cells (arrows) at each stage. The % of TUNEL positive cells increased with time in culture, peaking at D8 and statistical significance was determined for each stage with respect to D0 (p<0.05; n=3). C+ indicates cultures predigested with DNase II before TUNEL labeling, as a positive control. Thus, the increase in TUNEL labeling observed through the culture period was inversely correlated with the profile of Survivin and PCNA expression in cultures.