Mechanical pattern formation in biological tissue: Relax and go with the (viscous) flow

Mechanochemical models of pattern formation in biological tissue have helped us shed light on the role different mechanical cues have in cell aggregation phenomena, by considering the mechanical interaction between cells and the extracellular matrix (ECM). The cells and ECM are modelled as a linearly viscoelastic continuum, usually assumed to be a Kelvin-Voigt material, but this may not be the best model of viscoelasticity to use for biological tissue. We here extend the theory of mechanochemical pattern formation to include a wider variety of models of linear viscoelasticity. Our results clearly indicate that models of linear viscoelasticity presenting viscous flow (linear viscous, Maxwell, 3-parameter viscous model), which are better suited to represent soft tissue, have much higher pattern formation potential than those which do not (linear elastic, Kelvin-Voigt, standard linear solid model).