Tissues with disrupted nuclear dispersion have deeply compromised extension and pulsatile dynamics. (A) Still frames from a time-lapse movie of MT- embryo showing failure of nuclear dispersion indicated by nuclear crowding in the given imaging plane during a T1 cell intercalation event (related to Video 6). Image slice from ∼11 µm below the apical surface. (B) Comparing average length traces of vertical interfaces between control (vehicle-injected) and MT- (colchicine-injected) over the course of GBE. Error envelope indicates SEM. (C) Comparing the vertical interface length rate of change in control and MT- embryos. Negative values indicate contraction. For B and C, n = 238 interfaces for control from k = 4 embryos and n = 201 interfaces for MT- from k = 3 embryos. (D) Centroid length measurement for AB (blue) and CD (red) cells over 20 min for control and MT- embryos. Error envelopes indicate SD. (E) Extension rates of AB cells in control and MT- embryos. For D and E, n = 106 T1 transitions for control from k = 4 embryos and n = 87 T1 transitions for MT- from k = 3 embryos. (F) FFT analysis of oscillatory area changes for control and MT- embryos. The dotted line indicates the frequency at which the amplitude percent change was calculated in G. 0 μm depth indicates nuclear midplane. Positive values indicate apical and negative values indicate basal to the nuclear midplane. The color bar indicates the FFT amplitude in the frequency space. (G) FFT amplitude percent change from 0 μm (nuclear midplane) to −4 μm basal to the nuclear midplane at 0.008 Hz. Error bar indicates SEM. For F and G, n = 1,207 cells for control from k = 4 embryos and n = 420 cells for MT- embryos from k = 3 embryos. The measured n values are regardless of time points. Scale bar = 5 µm. Statistical significance was calculated using the Mann–Whitney U-test. *P < 0.05, ****P < 0.0001.