Abstract
Many organs, such as the gut or the spine are formed through folding of an epithelium. Whereas genetic regulation of epithelium folding has been investigated extensively, the nature of the mechanical forces driving this process remain largely unknown. Here we show that monolayers of identical cells proliferating on the inner surface of elastic spherical shells can spontaneously fold. By measuring the elastic deformation of the shell we inferred the forces acting within the monolayer. Using analytical and numerical theories at different scales, we found that the compressive stresses arising within the cell monolayer through proliferation quantitatively account for the shape of folds observed in experiments. Our study shows that forces arising from epithelium growth are sufficient to drive folding by buckling.
