Degree of apoptosis in cultured tissues. (A) Representative images of 5 μm-thick tissue sections labelled with terminal deoxynucleotdyl transferase (TdT). Few apoptotic nuclei are present in E2- and 2-hydroxypropyl-β-cyclodextrin (HBC)-treated and fresh tissues, while large numbers of apoptotic-positive nuclei are observed in damaged tissues. Fresh: control for viability; damaged: control for death; HBC-treated: control for E2 treatment. TdT (green) indicates apoptotic nuclei. Merged images with DAPI are shown in right panels. Scale bar, 100 μm. (B) The apoptotic index is low in E2- and HBC-treated and fresh tissues but significantly higher in damaged tissues (n = 3, *P = 0.05 for damaged versus E2- and HBC-treated and fresh). Data represent means ± standard deviation.