Fig. 2
Two distinct patterns of growth characterise the mandibular arch. a 3D renderings of cell membranes labelled by mTmG based on live light sheet microscopy. Whole arch (left) and local cell neighbour relations (middle and right with each colour representing one cell) are shown. Scale bar: 40 μm. b Distribution of numbers of cell neighbours in middle (red curve) and distal (blue curves) mandibular arch (n = 2 embryos, 202 middle cells and 244 distal cells examined, p < 0.05, chi-squared; scale bar: 40 μm. c Voronoi tesselation of mesenchymal nuclei to estimate cell shapes. d, e Colour-coded spatial distribution of cell shape index (S/V2/3) that correlates positively with liquid-like tissue phase (greatest in the middle region). f 4D tracks of a subset of mandibular arch cells are shown in two orthogonal views. Relatively directional tracks that were oriented distalward characterised the waist region, whereas short and tightly curved tracks characterise the bulbous region (representative of 3 embryos at 20 somite stage). g 3D dandelion plot of spatially colour-coded trajectories of cells at the start and end of a movie. Waist cells (red/orange) move predominantly outward whereas bulbous cells move in a relatively radial fashion. h Strain illustrated as deformation of a sagittal plane grid during a 150 min. movie. Nodes remain fixed to the same positions throughout the movie. Coloured lines to the left of each grid correspond to rostrocaudal rows of squares that correspond to dashed lines in i. Corresponds to Supplementary Movie 11. (Representative of 3 embryos at 20–21 somite stage.) i The proximodistal axis elongated (reflected by the positive εxx slope), while the midportion of the arch converged along the rostrocaudal axis (reflected by negative values of the εyy curve). Convergence of midportion tissue combined with expansion of distal tissue results in clockwise (positive εxy values) and counter-clockwise (negative εxy values) rotational deformation of adjacent regions, respectively (as reflected by the downward εxy slope). Dashed, coloured lines correspond to rostroacaudal rows of grid components of the strain tensor as depicted in h. The solid black line is the average of rostrocaudal strain tensors as it varied along the proximodistal axis. Source data are provided as a Source Data file
