Fig. 1
Cell cycle times and tissue properties are insufficient to explain mandibular arch shape. a Sagittal OPT renderings of the right mandibular arch in the mouse embryo at different stages. b Cell cycle time was measured in 24 adjacent regions (4 epithelial and 4 mesenchymal regions each within proximal, middle and distal arch) of the 19 somite stage mandibular arch. c, d Spatial variation of epithelial (c) and mesenchymal (d) cell cycle times in the mandibular arch. Cell division was more rapid in the proximal region for both epithelial and mesenchymal layers; n = 3 embryos at 20 somite stage, 15–35 cells examined for each of 12 epithelial regions per embryo, 50–75 cells examined for each of 12 mesenchymal regions per embryo; asterisks denote p < 0.05, Student’s t-test, error bars denote standard error of the mean (s.e.m.). e Tissue indentation by AFM was employed to measure properties of intact, live mouse embryos. f Elastic (Young’s) modulus (stiffness) of epithelium and mesenchyme. g Viscosity of whole tissue in proximal, middle and distal regions of the mandibular arch at 19 and 21 somite stages. For f and g, 15 separate sites in each proximal, middle and distal region were indented in triplicate (45 measurements per region) per embryo; n = 2 embryos per condition, asterisks denote statistical significance, p value range: 10−6 to 10−19, two-tailed t-test, error bars denote standard deviation. h Finite element simulation of 4 h of growth beginning from the actual 19 somite stage mandibular arch shape to predict 21 somite stage shape. The model incorporated experimentally measured spatial variation of cell cycle time, elasticity and viscosity. Simulated growth (in blue) results in an arch that is shorter and broader than the actual 21 somite stage arch. Source data are provided as a Source Data file
