Activation of dermal stem/progenitor cell proliferation after wounding. (A) At 3, 5, 7, 12, and 15 days after wounding, 5-bromo-2′-deoxyuridine (BrdU) labels in the normal skin tissues or wounded tissues were detected by immunohistochemistry. The percentage of BrdU-positive cells was also calculated, presented as mean ± standard deviation (C). C, control group (n = 3 per time point); d, days after wounding; L, long-term BrdU labeling group (n = 3 per time point); S, a single BrdU labeling group (n = 3 per time point). Scale bar = 100 μm. (B) BrdU (100 mg/kg) was injected intraperitoneally for three consecutive days (once per 12 hours) in nonwounded or wounded mice. Nonwounded dermal cells or granulation tissue-derived cells (GTCs) at 7 days post wounding were isolated and adherent cells were harvested for colony-forming assay. BrdU labels in the colonies were detected by immunofluorescence. Scale bar = 500 μm. (D) Quantification of the colonies. CFU, colony-forming unit. **P < 0.01.