TUNEL assay.

<p>(A) Images of apoptosis in sham-exposed controls (c) and in exposed samples, after 24 or 42 h of treatment onset (t). Immunoperoxidase and methyl green staining. Bar = 100 µm. Arrows point out apoptotic cells. (B) Apoptotic rate at 24 and 42 h: percents of total analyzed cells. Means ± SEM of three experimental replicates; three treated dishes and three controls per replicate. At 42 h the data dispersion in the treated group is very low, so that the error bars are not distinguishable. Asterisks identify statistical significance referring to the corresponding control group; **: 0.001≤P≤0.01; Student's t test. (C) Flow cytometry analysis of the cell cycle in exposed samples and in their corresponding controls. Cells were harvested at 24 h or 42 h after exposure onset and stained with propidium iodide for DNA quantification. Representative results from one single repeat. Each histogram represents the analysis of 20,000 events obtained from the corresponding samples.