Figure 3. Semithin section of seminiferous tubules in the young and aged mice. (A) Different stages of spermatogenesis (S) in the control group. (B) In the young mutant mice, the presence of small vacuoles between the spermatogenic cells was observed (arrowheads). (C) The aged testis characterized by the presence of lipofuscin pigments (arrowheads) and Sertoli cells hypertrophy (Sr). (D) Vacuolation in Sertoli cells (arrowhead), many of seminiferous tubules only contained spermatogonia (Sg) and spermatids (St). (E) Multinucleated giant cells (arrowheads) were frequently demonstrated in the seminiferous tubules. (F) Some degenerated spermatogonia with pyknotic nuclei (arrowhead) were observed with vacuolated spermatogenic cells (asterisks). (G–J) In melatonin treated group, the seminiferous tubules showed normal spermatogenesis (S), and many mature sperms (arrowheads).