Figure 7.

Decreased proliferation of dermal skin fibroblasts after UVB irradiation. A and B: Double immunostaining of PCNA (red) and vimentin (green) of third biopsy samples; control (A) and UVB irradiation (B); arrowheads mark proliferating fibroblasts in A. Nuclei are stained by Hoechst 33324 in blue. C and D: Immunostaining of PCNA (red) and nuclear staining with Hoechst 33324 of third biopsy samples. To facilitate determination of the proliferative index, blue nuclear staining was turned into green to indicate PCNA-positive nuclei in the overlay in yellow; control (C) and UVB-irradiated (D); arrowheads mark proliferating cells. E: Proliferative index expressed as percent PCNA-positive nuclei. F: Total cell number in the papillary dermis determined as nuclei per μm². Data are means ± SEM; control, n = 9, UVB, n = 10. P values were calculated by t-test; *P value <0.05. Original magnifications: ×400 (A and B); ×200 (C and D).