Active dynamics of tissue shear flow

TL;DR

This paper develops a hydrodynamic model for shear flow in epithelial tissues, incorporating cell topology and active cellular processes, revealing new rheological behaviors relevant to tissue morphogenesis.

Contribution

It introduces a novel hydrodynamic framework that includes topological cell rearrangements and active stresses, advancing understanding of tissue shear dynamics.

Findings

Identification of two active cellular processes affecting tissue shear

Discovery of memory effects leading to unique rheological behavior

Different shape changes driven by active processes depending on boundary conditions

Abstract

We present a hydrodynamic theory to describe shear flows in developing epithelial tissues. We introduce hydrodynamic fields corresponding to state properties of constituent cells as well as a contribution to overall tissue shear flow due to rearrangements in cell network topology. We then construct a generic linear constitutive equation for the shear rate due to topological rearrangements and we investigate a novel rheological behaviour resulting from memory effects in the tissue. We identify two distinct active cellular processes: generation of active stress in the tissue, and actively driven topological rearrangements. We find that these two active processes can produce distinct cellular and tissue shape changes, depending on boundary conditions applied on the tissue. Our findings have consequences for the understanding of tissue morphogenesis during development.