VL are initiated preferentially from actin filaments. MVECs expressing actin-GFP were imaged, at 10-s intervals, during the formation of diapedesis micro-wounds (asterisk). (a) Parent filaments (dashed blue line) accumulate and increase actin density that then burst into VL (arrowhead). Three morphologically distinct types of VL initiation types are typically seen: a crescent formed from the side of a filament, a spade whereby actin bursts from both sides of the filament, and a fan born from the intersection of two filaments. (b) Actin initiation nodes/spikes transition to VL with immediate directional adjustment to ensure directed VL radiation into the micro-wound (i and ii, arrowheads and dashed line). (iii) Quantitative analysis of the angle of spike protrusion with respect to its parent spike (representative measurement indicated by green and red dashed lines; n > 35). See Video 4. Bars: (a and b, i and ii) 5 µm; (b, iii) 2 µm.