a) Sequential revisits of hair follicles after DP-ablation during late regression. b) Box plot quantification of hair follicle length immediately following ablation, 4 days, and 11 days after DP-ablation (n = 20 follicles, in 4 mice; error bars represent max and min). c) Sequential revisits of hair follicles after partial DP-ablation during early regression (n = 12 follicles, in 3 mice). d) Schematic illustration of the results from mesenchymal DP-ablation experiments. DP-ablation during early regression results in failed elimination of the basal epithelium, while the inner layers continue upward in terminal differentiation, yet DP-ablation during late regression does not impair hair follicle regression. Asterisk indicates auto-fluorescence from the two-photon laser. Scale bars, 25 μm.