Figure 6. Immunohistochemistry of Bmi1 expression. A large number of Bmi1-positive cells were detectable in corneal endothelial cells from donors younger than 30 years of age (A). In contrast, Bmi1 expression was rarely detectable in corneal endothelium biopsies from donors older than 50 years of age (B) and the number of Bmi1-positive cells were noticeably decreased compared to samples from younger donors. Additionally, we found no staining in the negative control samples (C and D), indicating that the staining was specific. Magnification: 200×.