Hematopoietic gene expression is lost or severely reduced in Scl-depleted embryos. (A-H) Whole-mount embryos (15 × original magnification); lateral views; anterior, left; numbers of embryos represented in gray. (A, B) Erythroid gata1 and βE1 expression was lost in all morphants at 22 hpf. (C-E) In 26-hpf morphants, expression of primitive myeloid genes, pu.1, l-plastin, and mpo, was severely reduced. Remaining cells were restricted to the heart region (arrows) and posterior ICM (arrowheads). (F-H) HSCs were lost in Scl-depleted embryos. Runx1 and c-myb expression at 26 hpf associated with the DA was lost in scl morphants (F, G, arrows). In both cases, nonhematopoietic expression was unaffected (arrowheads).^30,35  Ikaros expression in primitive blood and HSCs was lost in 29-hpf morphants (C, arrow). In each case, any remaining expressing cells were restricted to the posterior ICM.