Movie S13.

Lateral branching of a Neurospora crassa hypha at a channel intersection, imaged with the fluorescent marker dye FM4-64 (left, pseudo-coloured red) and by bright-field imaging. The growth of the parent hypha is temporarily deflected by the vertical wall, but it subsequently realigns in a direction similar to that before the initial wall encounter (top left corner of the images). During this growth, the expanding subapical hyphal diameter eventually exceeds the channel width at the first intersection. The cell wall bulges, and the formation of a daughter Spitzenkörper precedes the establishment of an independent lateral daughter branch. The effect of directional memory is apparent in the movement of the primary hypha. Frame rate = 17.6 s per frame; total real-time duration 14 min 23 s.