Gene expression in CD45 ⁺ FL cells. (A–D and F) scRNA-seq of CD45⁺Lin⁻ (CD19⁻CD3⁻B220⁻Ter119⁻CD49b⁻CD90.2⁻) Vav1^iCreXpr1^fl/fl and Xpr1^fl/fl FL cells at E15.5, as in Fig. 3 A. (A) Plot showing average distribution of cell frequencies among clusters. (B) Heatmaps showing the top 10 DEGs of each cluster. Clusters are from Fig. 3 A. (C) Violin plots showing gene expression among clusters 6 (Xpr1^fl/fl (Cre⁻)) and 7 (Vav1^iCreXpr1^fl/fl (Cre⁺)). (D) UMAP plots of subsetted data (clusters 6 and 7 were used for subsetting). (E) Representative flow cytometry plots and frequencies and cell numbers (mean ± SD) of eosinophils (Eos) (pre-gated on CD45⁺CX3CR1⁻Ly6C⁻) extracted from E15.5 control (Xpr1^fl/fl and Xpr1^fl/+) and Vav1^iCreXpr1^fl/fl FLs. Data show n = 6–9 per group and are pooled from two independent experiments. Statistical analysis was performed using the Student’s t test. (F) Heatmap showing the top 10 DEGs of each cluster. Clusters used are from Fig. 3 B. (G) RNA velocity of Fig. 3 B. Arrows indicate direction of developmental trajectory. (H) Representative flow cytometry plots and frequencies of macrophages (Macs) and CD11b⁺ cells (CD11b⁺) (of CD45⁺ cells) generated from E15.5 control (Xpr1^fl/fl and Xpr1^fl/+) and Vav1^iCreXpr1^fl/fl FL cells cultured for 7 days in vitro with CSF-1. Data show n = 4–7 per group and are pooled from two independent experiments. Statistical analysis was performed using the Student’s t test. **P < 0.01 and ****P < 0.0001. ns, not significant.