Fig. 1.

Multiscale contributors to tissue mechanical properties. (A) Structural elements at the tissue, cell and molecular scale may contribute to bulk tissue mechanical properties. Germ layers in the dorsal axis are depicted in different colors: ectoderm (blue), mesoderm (red) and endoderm (yellow). (B) Time-dependent Young's modulus [E(t)] of dorsal tissues measured by uniaxial stress relaxation. Dorsal tissues from Xenopus laevis embryos are microsurgically isolated and loaded into the nanoNewton force measurement device (nNFMD). Tissues are compressed to a fixed strain (ε) and the compressive force is measured using a calibrated force transducer. Modulus is calculated from strain, force and the cross-sectional area measured after fixation (Zhou et al., 2009). (C) Residual elastic modulus [E(180)] determined from testing shows that dorsal tissues stiffen ∼150% between stages 14 and 21. Two clutches were tested (number of explants in each set indicated in parentheses below the plot). ***P<0.001 by Mann–Whitney U test. Error bars represent s.d. Note: explants were treated with 0.5% DMSO.