Decreased contribution of embryo-derived macrophages to cMΦ with age. (A) CX3CR1^creER:R26-yfp embryos were treated with TAM on E9 or E13 and analyzed on the day of delivery (P0) or 6 wk after delivery (P42). (B) Percentage of microglia-normalized YFP⁺ cMΦ and representative cytometry plots pregated on total cMΦ at P0 and P42 after E13 labeling. Bars show median (n = 9–13). ***, P ≤ 0.005, Mann-Whitney test. Data were pooled from two independent experiments. (C) Representative cytometry plot showing YFP⁺ within total cMΦ at P42 and percentage of microglia-normalized YFP⁺ cMΦ at P0 and P42 after E9 labeling. Bars show median (n = 7) *, P ≤ 0.05. Data were pooled from three independent experiments. (D) Representative cytometry plots showing YFP⁺ cells within MHCII⁻ and MHCII⁺ cMΦ at P0 and P42 after E13 labeling (n = 9–13). (E) Quantification of YFP⁺ cells within MHCII⁻ and MHCII⁺ cMΦ at P42 after E13 labeling. Bars show the median (n = 9–13). ***, P ≤ 0.005, Mann-Whitney test. Data were pooled from two independent experiments. (F) Adult TAM-treated CX3CR1^creER:R26-yfp mice were analyzed for YFP⁺ cMΦ and microglia at 1 and 4 wk after treatment. Percentage of microglia-normalized YFP⁺ cMΦ is shown as median with extreme samples as error bars (n = 3). Representative cytometry plots show YFP⁺ within total cMΦ. Unless otherwise indicated data in all panels are representative of two independent experiments.