Doc. dr. Jan Rozman, together with collaborators from the University of Lisbon and Oxford University, published the article “Multi-phase field model reveals internal dissipation is crucial for spontaneous hole formation in cell monolayers” in Nature Communications. Using a multi-phase field model to describe the mechanics of a monolayer tissue, they showed that intercellular friction can play a crucial role in the spontaneous formation of holes in the tissue. Intercellular friction plays a role similar to that of viscosity in a fluid, enabling the formation of longer-range correlations in cell movement, which in turn leads to more ordered dynamics of topological defects in the tissue. Consequently, pairs of defects can generate spiral flows, ultimately leading to the formation of an opening. The results are surprising in part because intercellular friction is almost always neglected in cell-resolution mechanical models of tissues.