Fig. 3. In-situ analysis of san mRNA expression. The san mRNA is expressed in the ventricular zone (black arrow) and diffusely throughout the brain at 28 hpf (A,B). Expression is also detectable at this stage in the posterior cardinal vein (green arrow) as illustrated by whole-mount (C) and in section (D). At 48 hpf, san expression is detectable in the notochord with patchy expression in the vein (E). The staining in the vein is clearly visible from sections through the trunk (F). The position of the dorsal aorta is indicated by the red arrow. The boxed region in C and E represent the region shown in the sections. nc, notochord; nt, neural tube.