Patterning-Mechanics Feedback Mechanism to Understand Axis Extension during Morphogenesis

Within the topic of morphogenesis, tissue elongation is a necessary process in all metazoans to shape their body plans which is not fully understood. For example, in the particular case of the limb, it has been shown that tissue elongation cannot be explained by either a localized proliferation of cells or their oriented divisions and, surprisingly, the tissue elongates perpendicular to the direction along which cell grow. Here we propose a mechanism of tissue elongation that couples the mechanical properties of cells with the concept of positional information to modulate the former in a location-dependent manner. To illustrate our proposal, we use morphogen gradient thresholds as well as Turing patterning system as the mean used by cells to “know” their relative positions within a primordium. Our numerical simulations are based on the vertex model system and we show that if the cell-cell adhesion is modulated as a function of the location of cells within a primordium, an auto-catalytic cell intercalation process develops and the tissue elongates. Moreover, our results reveal that cells grow perpendicular to the elongation direction as experimentally reported. Altogether, our results shed light on the tissue elongation problem and pave the way to better understand morphogenesis.