How growth-induced stresses guide shape changes during animal morphogenesis: Mechanisms and implications.

Morphogenesis, the process by which an organism develops its shape, is orchestrated by a complex interplay of genetic, biochemical, and mechanical factors. While myosin-driven contractility has been widely acknowledged as a critical driver of tissue shaping, emerging evidence suggests that differential growth (i.e. variations in growth rates within or between tissues) plays an equally vital role. Differential growth generates mechanical stresses that drive deformations at both cellular and tissue scales, shaping functional organ morphologies. This review introduces the core principles of growth mechanics in animal tissues and demonstrates how differential growth contributes to the generation of mechanical stresses that shape organs through processes such as folding, bending, and buckling, especially when different tissue layers or extracellular matrices impose external constraints. Furthermore, because cells can sense and respond to stresses, we highlight how integrating theoretical modelling with experimental data deepens our understanding of the feedback loops by which growth-induced stresses arise and mechanically guide functional shapes. Our aim is to engage developmental biologists by highlighting well-established insights from solid mechanics and plant biology on differential growth as a means to generate stress and shape tissue, complementing and extending the traditional focus on contractility.