Apico-basal intercalations enable the integrity of curved epithelia.

Non-invasive force inference based on imaging data has significantly advanced our understanding of the mechanical cues driving morphogenesis. In 2D studies of confluent tissues, these methods allow for the computation of forces acting on cells by analyzing their geometrical features. Here, we present a novel approach for 3D force and energy inference in curved epithelia. Specifically, we focus on tubular epithelia, which form the foundation of many vital organs, including the lungs, kidneys, and vasculature. Our technique analyzes the average mechanical behavior of cells along their apico-basal axis and is based on an optimal parametrization of a vertex model aimed at obtaining effective tissue parameters. We apply our method to data to investigate the mechanical consequences of different 3D cellular packing scenarios. Our results reveal that in squamous epithelia, prismatic cellular shapes are mechanically stable. However, in cubic/columnar tubes, prismatic shapes are incompatible with the adhesion required to maintain tissue integrity. In conclusion, this study indicates that in cubic/columnar epithelia, stability can only be achieved if cells undergo apico-basal intercalations and adopt an alternative shape: the scutoid.