Expression of EGFP in Tg(runx1P2:EGFP)–transgenic embryos. (A–I,K,L) Bright-field and (A′–I′,J,K′,L′) fluorescent images. (A) Lateral views of 6-somite (s) embryo showing EGFP expression in the notochord. (B) Lateral views of 12-somite embryo. EGFP is expressed in the spinal cord and notochord. (C) Lateral view of the trunk at 22 hpf. EGFP is present in the ventral wall of the dorsal aorta (DA; arrowhead) and the spinal cord (arrow). (D–F) Lateral views at 24 hpf showing EGFP in the brain and spinal cord (arrow, D,E), but not in the PBI (F). (G,H) Lateral views of 36 hpf embryo with EGFP-expressing cells between the DA and PCV along the whole trunk of the embryo (arrowhead). (I–L) Lateral views of 48 hpf embryo with many EGFP-positive cells in the AGM region between the trunk vessels (arrowhead). Round EGFP-positive cells with the morphology of hematopoietic cells are present between the DA and PCV in the AGM (arrowheads, K), and the caudal artery (CA) and caudal vein (CV) in the PBI (arrowheads, L).