(A) Uniform manifold approximation projection (UMAP) plots of scRNA-seq data of total endothelial lineage cells collected from TgBAC(etv2:Kaede)ci6, Tg(fli1:DsRed)um13; Tg(tp1:GFP)um14, and Tg(drl:H2B-dendra) embryos at 22–24 hpf. Clusters were named according to their gene expression: Erythroid, Lymphoid, General Endothelium (GE), Hemogenic Endothelium (HE), Pre-HSCs, Brain Vascular Endothelial Cells (BVECs-I and BVECs-II), Kidney Vascular Endothelial cells (KVECs), Endocardial Endothelial Cells (EECs), and somite-derived endothelial cells (SDECs). Color-coded marker gene expression levels are shown on corresponding clusters. A pink circle highlights the BVECs-I cluster. (B) Expression heatmap of 22–24 hpf single-cell transcriptome showing the top predicted differentially expressed marker genes across the different clusters. A red box highlights the BVECs-I cluster. (C’,C”) A list of brain-annotated genes was curated from the AmiGo annotation database and compared with the BVECs-I transcriptome. 63 genes were commonly expressed. Interestingly, several of these 63 genes were enriched within the BVECs-I cluster (C”; white boxed genes, D; enlarged circles).