Quantification of fibroblast density (number of PDGFRαH2BEGFP+ cells, right; n=3 biological replicates per time point) and dermis volume (left) with age (n=7 E12.5; n=8 P0, P6; n=9 E16.5, E17.5, P4; n=10 P10, P50; n=11 E10.5; n=12 E18.5, P2, P21; n=20 P12 biological replicates). 