Abstract

Abstract: Biological processes such as embryogenesis, wound healing and cancer progression, crucially rely on the ability of epithelial cells to coordinate their mechanical activity over length scales order of magnitudes larger than the typical cellular size. While regulated by various signalling pathways, it has recently become evident that this behavior can additionally hinge on a minimal toolkit of physical mechanisms, of which liquid crystal order is the most prominent example. In this talk, I will review our ongoing theoretical and experimental efforts toward deciphering liquid crystal order in epithelial tissues and its role in facilitating cells’ collective migration. In particular, I will show that certain kind of epithelial tissues feature a unique combination of nematic (i.e. 2-fold) and hexatic (i.e. 6-fold) order, coexisting at different length scales. Specifically, hexatic order is prominent at the cellular scale, while nematic order characterizes the structure of the monolayer at larger length scales. This hierarchal structure is expected to complement the complex network of regulatory pathways that tissues have at their disposal to coordinate the activity of individual cells to achieve multicellular organization.