Neural crest cells can take an alternative differentiation path toward a mesenchymal fate upon arrival at the aorta. t-SNE plots colored for the expression levels of mesenchymal genes Bmper (A) and Pdgfra (B). (C) t-SNE plot of Ngfr⁺ cells with Pdgfrβ⁺Ngfr^– mesenchymal cells sorted from the ventral E11 AGM. t-SNE plots of Ngfr⁺ cells (D) and Ngfr⁺ cells with Pdgfrβ⁺Ngfr^– mesenchymal cells (E) colored for the expression levels of Pdgfrb. (F) Immunohistochemical staining of E11 wild-type embryo cryosection for Dlk1 (red), Th (green), and DAPI (blue). (G) t-SNE gene expression plot colored for the expression of Cxcl12. (H) In situ hybridization staining on E11 wild-type AGM cryosection with a RNA probe for Cxcl12. Red lines outline ventral (V) Cxcl12-negative SNS patches. (I) Immunohistochemistry of E11.5 Wnt1-Cre⁺ tdTomato⁺ embryo with CD34 staining in yellow, tdTomato in magenta, and Pdgfrα in cyan. Asterisk denotes tdTomato⁺Pdgfrα^– SNS compartment; red boxes highlight tdTomato⁺Pdgfrα⁺ cells. Scale bar equals 100 μm. (J) Flow cytometry analysis of E11 Wnt1-Cre⁺ DsRed⁺ CD31^– AGM cells costained with an antibody to Pdgfrα. (K) Quantification of Ngfr⁺ Pdgfrα⁺ cells detected by flow cytometry analysis of E11 wild-type (WT) and p57Kip2 knockout (KO) AGM cells. A t-test was performed; error bars = SEM; n = 3. (L) Heatmap of the top 40 ventrally expressed genes in Ngfr⁺ cells. (M) t-SNE gene expression plots colored for the expression of genes upregulated in ventrally derived Ngfr1⁺ cells. D, dorsal; V, ventral.