EGFP expression in larval, juvenile, and adult runx1P2 transgenics. (A–D) Bright-field and (A′–D′) fluorescent images of transgenic larvae and juveniles. (A) Lateral view of the thymus at 4 dpf showing EGFP-positive thymocytes. (B) Dorsal view of 5-dpf transgenic embryo showing EGFP expression in the pronephros. (C,D) Lateral views of 1-month-old juvenile transgenic showing EGFP in the pronephros and mesonephros. (E–G) In situ hybridization for runx1 mRNA on a sagittal section of a 1-month-old wild-type fish. (F,G) Higher magnification of the pronephros and mesonephros shows runx1 mRNA localized to blood progenitors around the renal tubules. (H–J) Anti-GFP staining of a sagittal section of an adult runx1P2 transgenic showing EGFP-positive cells within the pronephros (arrowheads). (K–M) runx1 in situ hybridization on a sagittal section of the pronephros of wild-type adult. runx1 is expressed in hematopoietic cells around the renal tubules (arrowheads). Bars represent 200 μm (E,I,L), 50 μm (F,G,J,M), and 1 mm (H,K).