To verify the effectiveness of the above-mentioned fixative methods, mDF plus PFA was used to fix testes in cadmium-treated mice. Effects of cadmium stress on histological morphology in mouse testes were first analyzed. As shown in Fig. 7A,B,a and b, compact arrangements of seminiferous tubules and clear nuclear detail of germ cells were observed in all mouse testes. In addition, cadmium did not result in hyperemia, inflammatory infiltrations and cell necrosis in mouse testes (Fig. 7B and b). Effects of cadmium on DNA integrity in testes were then analyzed. As shown in Fig. 8Aand a false TUNEL-positive cells were hardly observed in untreated mouse testes. On the contrary, cadmium significantly caused a increase of apoptosis-positive tubules and apoptotic cells in mouse testes (Fig. 8A–D).