Fig. 2

Spatio-temporal distribution of the zebrafish Sox7 and Sox18 transcripts from bud stage to 28 hpf. (A,F) Posterior views of bud stage embryos indicating that Sox7 and Sox18 are expressed in stripes corresponding to the LPM. (B,G) Expression of Sox7 and Sox18 in the LPM persists throughout somitogenesis. Staining occurs at the anterior and the posterior parts of 5 somite embryos. (C,H) At 18 somite stage, a signal corresponding to Sox7 and Sox18 is seen in the presumptive axial vessels. (D) At 24 hpf, Sox7 is mostly expressed in the DA, the head vessels, the ICM and in two stripes located in the hindbrain. Preferential expression of Sox7 in the dorsal aorta is confirmed in the close-up view of the midtrunk vasculature shown in panel E. (I) Sox18 transcripts can be detected in the head vasculature, the ICM, the dorsal aorta and the axial vein. (J) Close-up view of the trunk showing Sox18 expression in both axial vessels at 24 hpf. Lateral (C–E,H–J) or dorsal views (B,G). Embryos are shown with anterior to the left. The developmental stage is indicated in each panel. DA: dorsal aorta; AV: axial vein; NC: notochord; LPM: lateral plate mesoderm; ICM: intermediate cell mass. (K–M) Double fluorescent in situ for the vascular marker Flk1 and Sox7 on wild-type embryos at 18 somite stage. Confocal views of transverse vibratome sections show that Sox7⁺ positive cells totally overlap with Flk1⁺ cells. (N–P) Double staining of Scl and Sox7 show a population of Scl⁺-Sox7^- cells located in the presumptive ICM (arrow in panel P). Panels M and P are merged views counterstained with Topro3 (blue).