foxc1a and foxc1b are required for definitive hematopoiesis in zebrafish. (A) Low-dose foxc1a/b (4/4 ng) morpholinos were injected into fertilized eggs of Tg(flk1:GFP) zebrafish. Fluorescence images of uninjected control and injected zebrafish are shown; (flk1:GFP) at 24 hpf, 66/75 intact; (flk1:GFP) at 28 hpf, 49/54 intact. (B) Low-dose foxc1a/b (4/4 ng) morpholinos were injected into fertilized eggs of wild-type zebrafish. In situ hybridization images with runx1, c-myb, and rag1 probes at indicated time points are shown. runx1, 17/35 decreased; c-myb, 11/26 decreased; rag1, 17/28 decreased.