a, PAGA analysis of fetal liver HSC/MPP, erythroid, megakaryocyte and mast cell lineages from Fig. 3a. Lines show connections; line thickness corresponds to the level of connectivity (low (thin) to high (thick) PAGA connectivity). b, Heat map showing min − max normalized expression of statistically significant (P < 0.001), dynamically variable genes from pseudotime analysis for erythroid, megakaryocyte and mast cell inferred trajectories. Transcription factors in bold, asterisks mark genes not previously implicated for the respective lineages. c, FDG visualization of fetal liver, skin and kidney HSC/MPP, MEMP, erythroid, megakaryocyte and mast cell lineages. d, Heat map showing the scaled ln-expression of selected marker genes in fetal liver, NLT and yolk sac subsets. e, PAGA connectivity scores of HSC/MPP, erythroid, megakaryocyte and mast cell lineages between fetal liver, skin, kidney (K) and yolk sac. f, Representative immunohistochemical staining of sequential sections of 8 PCW fetal skin for endothelium (CD34+) and erythroblasts (nucleated and GYPA+), nuclei stained with blue alkaline phosphatase. Zoom in of insets (right) bordered with black (top) indicate nucleated cells stained positive for GYPA within CD34+ blood vessels, and those bordered with red (bottom) indicate nucleated GYPA+ cells outside CD34+ blood vessels. Scale bars, 100 μm. g, Representative confocal fluorescence microscopy of embryo (5 PCW) hand skin. Scale bar, 10 μm; red, TO-PRO-3 nuclei; green, GYPA (see also Supplementary Video 2 showing light-sheet fluorescence microscopy). The arrowhead indicates extravascular nucleated erythroid cells. h, Stacked bar plots (left) showing percentage (mean ± s.d.) of fetal liver (red), skin (blue) and kidney (green) HSC/MPP, MEMP, erythroid, megakaryocyte and mast cells in each stage of the cell cycle (G1 (navy), G2M (blue) and S (white) phase), and ln-normalized median expression of MKI67 transcript (right) in corresponding liver vs NLT cell types (total percent of MKI67-expressing cells shown above plots; each dot represents a single cell). *P < 0.05, **P < 0.01 and ***P < 0.005.