Figure 6.

Influence of repeated exposure to IRA on epidermal thickness and suprabasal cell proliferation in human skin equivalents. (a) Representative images of control and IRA‐irradiated groups were acquired on day 5. Scale bar represents 50 μm. (b, c) Quantification of epidermal cell layer and stratum corneum thickness (μm) at the indicated time points. Data are the mean ± SE of five skin equivalents. *P < 0.05, **P < 0.01 vs control by unpaired two‐tailed Student’s t‐test. (d) The number of Ki‐67‐positive cells was assessed by immunocytochemistry on day 5. Data are the mean ± SE of five skin equivalents. **P < 0.01 vs control by unpaired two‐tailed Student’s t‐test. Scale bar represents 100 μm.