(A–L) etv2, flk1/kdrl, and fli1a expression analysis in trunk angioblasts at the 10-, 15-, 18-, and 22-somite stages. etv2 expression is observed in the medial (arrowheads) and lateral (arrows) angioblasts. flk1/kdrl and fli1a expression is initially restricted to the medial angioblasts (B and C) with very weak observed expression in the lateral angioblasts in 15- to 22-somite stage embryos (E–K; F–L).
(M–O) etv2 expression in migrating medial angioblasts at the 11- to 14-somite stages. Note that the migration wave progresses in the anterior to posterior direction. The lateral angioblasts migrate later at the 16- to 22-somite stages (G and J). Dorsal view of the trunk and tail region of flatmounted embryos. Anterior is to the left. Scale bar, 100 μm.
See also Figures S1 and S2, and Movies S1, S2, S3, and S4.