Figure 3.Representative histograms obtained for test samples. The calculation of TUNEL-positive sperm cells (with fragmented DNA) based on data analysis presented in Figure 1. FL3 – red fluorescence channel for PI-stained cells, FL3 – red fluorescence channel for PI-stained cells, FL1 – green fluorescence channel for FITC-streptavidin-biotin-dNTP-labelled cells, TUNEL – terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling, PI – propidium iodide.