Percentage of PDGFRαH2BEGFP+ cells in G1 cell cycle phase with age (n=1 E12.5; n=2 P2, P10; n=3 E16.5, E17, P0; n=4 E10.5; n=5 E17.5, E18.5, P50; n=7 P4 biological replicates) fitted using an exponential model. 