Fig. 6

Cell division perturbs local velocity field more in smaller microtubes. a Average velocity of cell front of mitomycin C-treated H1-GFP MDCKs in tubes of different diameters (25, 50, 75, 100, 150, and 250 μm, from left to right), (n = 6 from three independent experiments in each condition) in comparison with that of H1-GFP MDCKs (taken from Fig. 4d). b Tubular confinement does not affect MDCK proliferation. c Representative images of cell nucleus (H1-GFP MDCKs) in a 50 μm diameter tubular tissue moving upward (green arrow). Green circle shows fixed region (radius ~25 μm), where velocity field vectors are averaged to determine the perturbation by a cell division event at t = 0 min, defined as the first instance where two daughter cells (red arrows) emerged from a dividing cell (blue arrow). Scale bar: 50 μm. d Average velocity in fixed region related to division as a function of time, further averaged over many division events. (25 μm: n = 79, 50 μm: n = 130, 75 μm: n = 166, 100 μm: n = 286, 150 μm: n = 311, 250 μm: n = 348, from two independent experiments per condition). e Schematic showing how the distance perturbation factor is calculated from the average velocity curves in d for a defined radius of fixed region, r. f Average distance perturbation factor as a function of tube diameter, where the factor is calculated for different pairs of parameters (r, δt), with r = 18.6, 21.1, 23.6, 26.0 μm and δt = 10, 20, 30 min. g, h Kymograph of the average longitudinal (g) and circumferential velocity (h) of mitomycin-treated H1-GFP MDCK TCSs migrating in different microtubes (from left to right: 25, 100, and 250 μm). Black dash lines indicate velocity waves that propagate opposite to the collective migration direction. t-test, *P < 0.05, **P < 0.01, ***P < 0.001, NS non-significant, for each condition, t-test has been performed between each microtube diameter and 25 μm, unless otherwise indicated by line. All data are presented as mean ± s.e.m.