An active matter model captures the spatial dynamics of actomyosin oscillations during morphogenesis

The apicomedial actomyosin network is crucial for generating mechanical forces in cells. Oscillatory behaviour of this contractile network is commonly observed before or during significant morphogenetic events. For instance, during the development of the Drosophila adult abdominal epidermis, larval epithelial cells (LECs) undergo pulsed contractions before being replaced by histoblasts. These contractions involve the formation of contracted regions of concentrated actin and myosin. However, the emergence and control of pulsed contractions are not fully understood. Here, we combined in vivo 4D microscopy with numerical simulations of an active elastomer model applied to realistic cell geometries and boundary conditions to study LEC actomyosin dynamics. The active elastomer model was able to reproduce in vivo observations quantitatively. We also characterised the relationship between cell shape, cell polarity, and actomyosin network parameters with the spatiotemporal characteristics of the contractile network both in vivo and in simulations. Our results show that cell geometry, accompanied by boundary conditions which reflect the cells polarity, is essential to understand the dynamics of the apicomedial actomyosin network. Moreover, our findings support the notion that spatiotemporal oscillatory behaviour of the actomyosin network is an emergent property of the actomyosin network, rather than driven by upstream signalling.