WSS induces hematopoietic gene expression and progenitor activity. E9.5 PSp- or E10.5 AGM-derived cells were cultured for 36 h in the presence of 5 dyn/cm² WSS or static (<0.0001 dyn/cm²) conditions. (A) qRT-PCR of E9.5 PSp demonstrates that WSS induces widespread up-regulation of genes known to be critical regulators of definitive hematopoiesis and lymphopoiesis (n = 5 independent experiments; two-tailed Student’s t test or Mann–Whitney rank sum: *, P < 0.05; **, P < 0.01). (B) Representative flow cytometry plots show distribution of hemogenic endothelial markers (CD144/VE-Cadherin and c-kit) in the cultured populations after 36 h of WSS exposure. Live (DAPI⁻) CD144⁺ and CD144⁺ ckit⁺ gates are depicted. (C) CD144⁺ ckit⁺ CD45^−/+ populations are increased by WSS (n = 4 independent experiments; two-tailed Student’s t test: *, P < 0.05). Data are represented as mean ± SEM.