Abstract

Biological tissues self-organise thanks to patterning processes coupled to cellular mechanical interactions, which play a fundamental role in driving coordinated cell movements.  Here I will discuss how polarity-oriented active mechanical forces drive collective cell motion in three dimensions. I will introduce the framework of « interacting active surfaces », which describe cell aggregates as mechanically coupled flowing active surfaces. I will discuss the three-dimensional rotational motion of cell doublets, which arise from polarised distribution of myosins in the actomyosin cortex of the doublet cells. I will discuss how the shape of the doublet interface can be understood from an analysis of the group of symmetry of the cell doublet and application of the Curie principle. I will then discuss how principles of polarity dynamics and polarity-based mechanical interaction can act in larger three-dimensional cellular aggregates.