Fig. 7

The Seeding of Caudal Hematopoiesis Requires Blood Circulation(A–L) Real-time follow-up of representative control and silent heart morphant [CD41-gfp; gata1-dsred] embryo, at the trunk (A–F) and tail (G–L) level; green+red fluorescence overlaid on DIC images (lateral views, rostral left). In the control embryo, the flow of circulating DsRed⁺ primitive erythrocytes delineates blood circulation; GFP⁺ cells develops in the tail (G–I), barely in the trunk (A–C). In the silent heart morphant, many of the noncirculating primitive erythroblasts are gathered in a big mass in the rostral trunk (an arrowhead indicates its caudal border) (D–F); GFP⁺ cells develop in the trunk ([D]–[F], lower panels show green channel alone) and not in the tail (J–L), despite the presence of a normal CV plexus at 2 dpf ([J], arrowheads). Scale bar represents 100 μm. (M and N) In situ hybridization for c-myb in control and sih morphant embryos.