BABL/c male mice (6 to 8 weeks old, 20–27 g in weight) were housed in a temperature (23 ± 1 °C)- and humidity (60 ± 5 %)-controlled room at a constant 12-/12-h light/dark cycle. All procedures were performed in accordance with the Ethics Committee of the Institute of Zoology, Chinese Academy of Sciences. After 1 week of adaptation, 80 mice were randomly divided into four groups of equal size and dosed by oral gavage with either vehicle (Milli-Q water) or 1.25, 5, or 20 mg/kg/d PFOA (dissolved in Milli-Q water) for 28 consecutive days. After treatment, all mice and testes were sampled for analysis. The right testes of three mice were fixed in 4 % paraformaldehyde for immunofluorescence microscopy, while the remaining testes were immediately frozen in liquid nitrogen and stored at −80 °C for later analysis.