Figure 5.

Changes in telomere length as a function of population doubling. DNA was isolated from chicken embryonic fibroblasts at points throughout the lifespan of the culture. The DNA was digested with HinfI + AluI, and telomere length was measured by hybridization to the G-strand overhang. The population doubling at the time of sample isolation is shown above each lane. Size markers are shown in lanes 1 and 2. Sizes in kilobases are indicated on the left. (B) Mean telomere length was calculated from the data shown in A and plotted as a function of population doubling.