Figure 5: Characterization of mouse testicular stem cells using SCA-1 (for VSELs) and GFRa (for SSCs) (Ai-iii) Cell surface GFRa expression is observed in larger cells in control mice testicular smears. Smaller magnetically separated SCA-1 positive cells were negative for GFRa in both control (Bi-iv) and busulphan treated testicular smears (Ci-iv). (D) Expression of GFRa in larger cells was further validated by flow cytometry based on size calibration beads. P1 includes cells between 2-8 μm and P2 includes cells >8 μm. In control testicular cell suspension (E), GFRa positive cells were seen only in P2 population as observed by the shift in PE positive population i.e. P6 (G) as compared to unstained. No GFRa positive cells are seen in P1 population (F).