Movie S1.

Unconstrained hyphal growth in a wide, 100x100x10 μm PDMS-made chamber. The microtubules were genetically GFP-tagged (pseudo-coloured green), and the hypha was loaded with the marker dye FM4-64 (pseudo-coloured red) labelling the Spitzenkörper as a bright red object within the extreme hyphal apex. The video shows that the Spitzenkörper maintains a central position with temporary side-ways deviations resulting in small changes in the growth direction. Frame rate = 12.6 s per frame.