Snapshots of
Movie EV1. Time lapse of embryonic organotypic slice culture from CD41:YFP (yellow): H2B‐GFP (blue) reporter mouse shows the emergence of a single cell protruding from the endothelial layer into the aortic lumen. Scale bars: 50 μm (overview), 10 μm (magnification). Time expressed in hh:mm:ss.