Loss of Ddx18 results in reduced number of primitive myeloid and erythroid cells. (A-D) Embryos (27 hpf) showing WISH for mpx (black) and band3 (slc4a1; red) to distinguish myeloid and erythroid lineage cells, respectively. Lateral view with head to the left and dorsal upward. ddx18^hi1727 mutants have markedly reduced myeloid cells and erythroid cells (C) and close-up view of the ICM (D), compared with siblings (A) and close-up of ICM (B). (E) Bar chart quantifying numbers of mpx, band3, and l-plastin cells per embryo at 27 hpf. **P < .002, Student t test. (F-G) Brightfield images of 52-hpf embryos showing reduced number of erythroid cells in the ducts of Cuvier (arrowhead) in ddx18^hi1727 mutants (G) compared with sibling controls (F).