Anomalous glassy dynamics in simple models of biological tissue

The analogy between colloidal glasses and epithelial tissues provides a powerful framework for
understanding the interplay between rigidity and motility in biological tissues. Here we present a detailed study of the role of fluctuations on the disordered rigidity transition of a Voronoi model that describes a confluent tissue monolayer as a network of polygons determined by a Voronoi tessellation of the cell positions. We show that just as in particulate glasses, the dynamics slow as the system approaches the glass transition. However, in contrast to the super-Arrhenius behavior associated with growing energy barriers seen in particulate glasses, the Voronoi model displays sub-Arrhenius behavior. Moreover, the low-frequency spectrum indicates that the potential energy landscape becomes flatter at lower temperatures, with little evidence for quasi-localized excitations, which
is also in marked contrast to structural glasses. This suggests that glassy behavior in Voronoi models, and perhaps biological tissues, is distinct from that in many glasses, and may provide unique insight into the glass transition itself.