Figure 1.

Flow cytometry analysis of fate‐mapped monocytes and macrophages.

A. CX3CR1^creER R26^tdTomato reporter mice were labeled in utero, embryonic day 14.5 (E14.5), by tamoxifen gavage of pregnant mothers. Labeled pups were weaned and then sacrificed at 8 weeks of age and assessed for labeling efficiency in brain microglia and blood. (Left panel) Brain microglia (CD45+ CD11b+ CD64+, Red line) were labeled with >98% efficiency from embryonic exposure to tamoxifen, whereas unlabeled age‐matched mice showed no labeling (control, Gray line). (Right panel) In the same mice, blood at 8 weeks of age showed no labeling of blood monocytes (CD45+ CD11b+ Ly6G‐ CD115+) in E14.5 labeled (Red) or control (Gray).

B. CCR2^creER R26^tdTomato reporter mice were gavaged with a single dose of tamoxifen, and labeling efficiency in the blood was analyzed 16 hr later. T cells (CD45+ TCRβ+), B Cells (CD45+ CD19+), Neutrophil (CD45+ CD11b+ Ly6G+), Ly6C‐ Monocytes (CD45+ CD11b+ Ly6G‐ CD115+ Ly6C‐), and Ly6C+ Monocytes (CD45+ CD11b+ Ly6G‐ CD115+ Ly6C+) were assessed for tdTomato labeling, where Ly6C monocytes were efficiently labeled.