Fig. 1. Stages of early vasculogenesis. (A-C) Taken from Movie 1 at http://dev.biologists.org/supplemental. Changes in the Cy3-QH1 pulse labeled primordial endothelial cell population over a 12 hour time period, with corresponding DIC images (insets). (D) The merged image of the pulse-labeled PECs (red) and the post-experimentally Cy2-QH1 labeled vasculature (green). The red and green open circles mark the same PECs and endothelial structures whose movements are followed in each panel. Note the extensive lateral-to-medial movement of those foci lying most distal to the midline axis (red lines). By comparison, those in a more proximal position show lesser displacements. The cyan colored box indicates the field that is enlarged in Fig. 2 and serves as a frame of reference between panels. The box is 400x400 µm with the upper right corner centered on the lateral edge of the third formed somite (yellow asterisks, inset), 160 µm from the midline. All images are from the ventral aspect. The yellow arrowheads in C (inset) indicate the developing pronephros. sv, sinus venosus; nf, neural folds; ao, area opaca; nc, notochord.