Fig. 3. Atm reactivation in Atm^TgERT2-LBDAtm^−/− mice reconstitutes male germ cell development.

a Representative image of ovaries sections stained with H&E n = 3 females analyzed for each genotype. Scale bar = 100 μm. b Testis picture of two months Atm^+/+, +TAM Atm^{Tg ERT2-LBD}Atm^−/−, Atm^{Tg ERT2-LBD}Atm^−/−, and Atm^−/− old mice. Scale bar = 5 mm. Histogram shows the mean value ± SEM of testis weight (n = 5 mice for each group). **P < 0.01 and ****P < 0.0001. H&E staining highlighted the presence of elongated spermatids (asterisks) and also spermatozoa (black arrowheads). Scale bar = 50 μm. c Epididymal spermatozoa pictures isolated from two months old Atm^+/+ and +TAM Atm^{Tg ERT2-LBD}Atm^−/−mice. Images were captured in white field at the Nikon Eclipse Ti-S microscope. Scale bar = 10 μm. Histogram of sperm count is shown as mean value ± SEM (n = 6 mice for each group). ****P < 0.0001. d Flow chart of Atm restoration in 45 days old mice treated with tamoxifen and sacrificed 17 days after the injection. Testes picture and testis weight at day 17 is shown. Scale bar = 5 mm. *P < 0.05. e H&E section staining of Atm^+/+, +TAM Atm^{Tg ERT2-LBD}Atm^−/−,+ORCH Atm^{Tg ERT2-LBD} Atm^−/−, and Atm^−/− testes. Asterisks show round and elongated spermatids in +TAM Atm^{Tg ERT2-LBD}Atm^−/− seminiferous tubules. Immunofluorescence for H2AX phosphorylation was performed in adjacent sections. Scale bar = 50 μm. Magnification shows γ-H2AX staining in sex body of pachytene spermatocytes. DAPI was used to stain nuclei