Fig. 4

Optimization of the mouse model for transplantation and transplantation confirmation of post-thawed SSCs. In the control group, the seminiferous tubules are completely filled showing all maturation stages of the germinal epithelium from spermatogonia to spermatozoa (a). In the busulfan group, most tubules are empty and the germinal epithelium in the seminiferous tubules is severely disrupted (b) (scale bar = 100 m). Two weeks after transplantation, homing of DiI-labeled SSCs (DiI.⁺ germ cells) in the basement membrane of seminiferous tubules as confirmed by immunofluorescence staining of recipient testes indicated successful transplantation (c). The blue color in same section of the testicular tissue indicated nuclei stained by DAPI (d). Merged images are reported in panel (e) (scale bars: 50 μm)