DPFCs, but not highly polyploid megakaryocytes, are distributed across the entire conceptus by E10.5. (A) (i) Representative 3-dimensional projection of confocal z-stacks from a chemically cleared E10.5 embryo. CD41⁺CD42D⁺ cells are observed throughout vascularized regions, including the head and somites (n = 10; bar, 200 μm). (ii-iii) Representative 3-dimensional projection of confocal z-stacks from glycerol-cleared organs revealing the presence of CD41⁺CD42D⁺ cells (arrows) and platelets (arrowheads) in the E10.5 (ii) liver and (iii) placenta. Bars, 20 μm. (B) Quantification of absolute numbers of CD41^highCD42D⁺ cells in key hematogenic organs of the E10.5 conceptus reveals a significant enrichment in the YS despite the onset of circulation. Data are cumulative of 3 independent experiments, **P < .01; ***P < .001. (C) DNA content analysis on pooled embryonic samples demonstrating that all CD41^highCD42D⁺ cells in the YS, peripheral blood (PB), placenta (Plac), and liver are low ploidy (2n-4n), with the majority in a diploid state. Those in the liver had a greater proportion of cells in S-phase and 4n. (n = 3).