Figure 4.
Labeling index and proliferation fraction of the bronchial epithelium. The total labeling index for the bronchial epithelium (A) was defined as the percentage of BrdU-labeled nuclei/total number of nuclei. The labeling index for each cell type (B) was defined as the percentage of dual-positive CCSP/BrdU, GSI-B4/BrdU, or K14/BrdU cells divided by the total number of cells in each category. The proliferative fraction (C) was defined as the percentage of BrdU-labeled cells of each cell type divided by the total number of BrdU-labeled nuclei. Each value was determined for control (Ctrl) and naphthalene-treated mice that had been recovered 1.5 to 9 days (d) and is reported as the mean ± SEM (n = 4 to 5 for each group). *, P < 0.05 and †, P < 0.01 relative to values in untreated control mice.