Figure 7.
p16INK4a and Bmi1 staining of three biopsies from each age group, shown as the number of positive cells counted in a total 10 visual fields for each sample. The average number of p16INK4a positive cells per field was less than 5 in donors younger than 30 years of age, 10 in donors older than 30 of years and younger than 50 years of age, and 30 in donors older than 50 years of age (A). The number of Bmi1 positive cells was determined in the same way. The average number of Bmi1-positive cells per field was 50 in donors younger than 30 years of age, 30 in donors older than 30 of years and younger than 50 years of age, and 20 in donors older than 50 years of age (B).