Movie S4.

Dramatic reduction in distal blood flow with proximal steal effect. Single-plane movie from a two-photon imaging stack taken at a late time point in AV shunt progression in a Tie2-tTA; TRE-Notch4* mutant mouse. Movement of dark-red blood cells can be observed by contrast Texas-Red–dextran labeled plasma. Slowly moving red blood cells can be observed as distinct spheres, and quickly moving blood cells appear as streaks. Blood flow and vessel diameter was reduced in this distal branch over time as the proximal connection grew.