Movie 2.

Cell shape changes under tension. HH4 mem-GFP+ anterior neural plate area was imaged through bidirectional stretching. Probe force constant k = 0.2 N m^-1. Voltage controlling the double-motor was increased by 5 V steps (to prevent tissue tearing) to eventually 40 V and held for 1 hr. Timestamp shows minutes and seconds (imaging frequency was 2 Hz). The movie shows the first 4 min of the experiment (a focus adjustment around 03:45). Probes can be seen exiting the field of view on the sides as the stepwise stretching continued. Tissue and cells can be seen to change shape in response to the imposed tension. Scale bar: 100 μm.