GATA1 and NF-E2 operate within the DPFC lineage in a manner consistent with adult MKs. (A) (i) Representative flow cytometry plots from E8.5 age-matched (8 somite pairs) wild-type and Gata1^ΔHS/y mutant YSs stained with anti-CD41 and -VECAD antibodies. Pre-DPFCs are gated in black, and the hematopoietic progenitor population is in blue. (ii-iii) Quantification of pre-DPFC and HPC numbers per YS at E8.5 according to discrete somite pair stages. Linear regression analysis revealed a DPFC lineage-specific phenotype, in which an early expansion in pre-DPFCs occurs from the 8 somite pair stage, whereas the HPC population remains quantitatively unaltered. ns, not significant, *P < .05. (B) (i) Representative flow cytometry plots and (ii) absolute quantification of E10.5 YS DPFCs numbers in individual wild-type and Gata1^ΔHS mutant embryos. ***P < .0001. Bars, standard deviation. (C) Representative 3-dimensional projection of confocal z-stacks from (i) wild-type and (ii) Nfe2^−/− E10.5 intact YSs stained with anti-CD41 (red) and -CD42D (green) antibodies. DPFCs are indicated by arrowheads and platelets by arrows. n = 13. (D-E) Quantification of (D) DPFC numbers in the YS and (E) platelets in the peripheral blood of E10.5 individual wild-type and Nfe2^−/− embryos. n = 4 to 10; bar represents standard deviation. ns, not significant. *P < .05. Dashed line represents the upper limit of maternal platelet contamination to each sample, as previously described.²⁸