TUNEL assay for apoptosis detection

Paraffin sections were prepared using conventional methods. According to the TUNEL Apoptosis Detection Kit (Sigma-Aldrich), the samples were washed three times with phosphate buffer and soaked in methanol at -20° C for 15 min. Samples were then washed three times with phosphate buffer and covered with a balanced salt buffer for 30 min. The tissue was covered with the reaction complex, incubated at room temperature for 60 min, washed with phosphate buffer three times, and then sealed. Finally, a fluorescence analyzer was used for analysis.