Figure 7. Timd4⁺ thymic macrophages are derived from Cx3cr1⁺ cells during embryonic development.

(A) Example flow cytometry plots for the expression of Cx3cr1^GFP and TIM4 on thymic macrophages at different times during embryonic development (E14.5, E17.5), immediately after birth, at 7 days, and 6 weeks of age. (B) Frequencies of Timd4⁺Cx3cr1⁻ (Timd4 single-positive or Timd4SP), Timd4⁺Cx3cr1⁺ (double-positive or DP), and Cx3cr1⁺Timd4⁻ (Cx3cr1 single-positive or Cx3cr1SP) thymic macrophages at the indicated time points. (C) Kinetics of the changes in different subpopulations of thymic macrophages from E14.5–6 weeks. (D) Frequencies at E15.5 and E19.5 of GFP-labeled cells among TIM4⁺ or TIM4⁻ cells in Cx3cr1^CreER × ROSA26^LSL-GFP embryos treated with 4-OHT at E9.5. (E) Scheme of the fate-mapping experiments showing the relationship between Cx3cr1⁺ and Timd4⁺ thymic macrophages during embryonic development. E15.5 pregnant ROSA26^LSL-GFP mice mated with Cx3cr1^CreER males were injected with 4-hydroxytamoxifen (4-OHT) and sacrificed at E19.5. (F) Representative flow cytometry staining for TIM4 and CX3CR1 in fate-mapped GFP⁺ thymic macrophages at E19.5. The panel to the right is the isotype control for CX3CR1-PE staining. (G) Frequencies of TIM4⁺CX3CR1⁻ cells among fate-mapped GFP⁺ macrophages. Data are shown as meanSEM and are from at least two independent experiments for each panel. Each symbol is an individual mouse or embryo.