Germ cell sorting was as described (Gainetdinov et al., 2018 (link); Yu et al., 2022 (link)). Briefly, we de-capsulated the testis specimens and incubated with 1× Gey′s Balanced Salt Solution (GBSS, Sigma, G9779) containing 0.4 mg/ml collagenase type 4 (Worthington; LS004188) at 33°C for 15 min. Thereafter, we washed the seminiferous tubules twice with 1× GBSS, and incubated them with 1× GBSS containing 0.5 mg/ml trypsin and 1 μg/ml DNase I at 33°C for 15 min. Next, the seminiferous tubules were gently pipetted up and down for 3 min through a Pasteur pipette to homogenize at 4°C on. Trypsin was inactivated with fetal bovine serum (FBS; f.c. 7.5% [v/v]), and the cell suspension was passed through a pre-wetted 70 μm cell strainer. Cells were recovered by centrifugation at 300 × g at 4°C for 10 min, resuspended in 1× GBSS containing 5% (v/v) FBS, 1 μg/ml DNase I, and 5 μg/ml Hoechst 33342 (Thermo Fisher, 62249), and incubated at 33°C for 45 min rotating at 150 rpm. Finally, we added propidium iodide (0.2 μg/ml, f.c.; Thermo Fisher, P3566) directly to the cells which were further filtered through a pre-wetted 40 μm cell strainer. Cell sorting (FACS Core, University of Massachusetts Medical School) was performed as described (Bastos et al., 2005 (link); Yu et al., 2022 (link)).