Fig. 9. Model of the construction of a zebrafish ISV. An intersegmental vessel (ISV) is composed of three types of endothelial cells, distinguished by their morphologies. The dorsal connection to the DLAV is a T-shaped cell (blue); the ventral connection to the aorta is an inverted ‘T’ (red). The connecting cell (green) courses between the somites ventral to the notochord-neural tube interface, and appears not to follow the somite boundary dorsally, where it runs directly to the DLAV..