Knockdown of primitive myeloid lineage spib.a transcription factor results in loss of myeloid gene candidate expression in the anterior ventral blood island (aVBI) of stage 23 embryos. A–J: Normal expression of genes in the aVBI of uninjected control embryos. A′ –J′ : Reduced aVBI expression of genes in the embryos injected dorsally at 4-cell stage with 40 ng e1i1 spib.a morpholino. A+A′ , spib.a. B+B′ , mpo. C+C′ , mmp7. D+D′ , adam28. E+E′ , coro1a. F+F′, ctss. G+G′ , dstn. H+H′, fmnl1. I+I′ , timp-1. J+J′ , ptpn6.