GFP expression pattern in Tg(fmyhc2:gfp) transgenic line. In this line, the Tol2-based enhancer trap element was inserted in between the fast muscle heavy chain genes fmyhc2.1/myhz2 and fmyhc2.2/myhc4. (A) GFP expression in somites of a transgenic embryo at 22s stage. (B) Endogenous fmyhc2.1 and fmhc2.2 genes share a similar expression pattern in 22s wild-type embryos. (C-C′′) GFP expression pattern in a 28-hpf embryo with two optical cross sections (C′, C′′) at indicated positions. Note that GFP expression was restricted to somites. (D) GFP expression in adult fish (laterally positioned). (E) Some GFP+ hematopoietic cells were circulating through the heart in an embryo at 36 hpf. See also Movie S2. (F) Flow cytometry results showing the existence of GFP+ blood cells in the embryonic circulation (left) and in the circulation of adults (right). Embryonic blood cells were sucked from the hearts of 5-10 embryos at 28 hpf. Adult blood cells were taken from the heart. The showed were representative results with average (Av) from 3 independent experiments in parenthesis.