A scaling law for epithelial tissue rheology

Predictive mechanistic understanding of morphogenesis absolutely requires quantitative knowledge of the mechanical properties of embryonic tissues. Our lab has recently established a set of experimental tools that have allowed us to directly probe tissue material properties in the living early embryo of Drosophila melanogaster . Here, we develop a simple quantitative theory explaining our central experimental observation: when subjected to concentrated constant pulling force, epithelium deforms following a power law with an exponent of 1 / 2. Our analysis explains this finding in terms of two physical effects: ([1][1]) actin turnover and ([2][2]) geometric nonlinearity due to the floppy topology of the cellular network, and has additionally allowed us to measure the effective spring constant of a cellular edge. ### Competing Interest Statement The authors have declared no competing interest. [1]: #ref-1 [2]: #ref-2