TUNEL (red) and Sytox (green) in sham irradiated (A), and at 6 (B), 12 (C),18 (D), and 24 (E) hours post irradiation (hpi). In sham irradiated controls, very few apoptotic cells are observed in taste epithelium; TUNEL positive cells, when present, were located within taste buds (white arrowhead). Following irradiation, the number of apoptotic cells increased, and most were located at the basement membrane (white arrows point to examples). (F) The number of TUNEL+ cells peaked at 18 hpi. one-way ANOVA, Tukey post hoc test; n=3–5 mice per time point; * p < 0.01.