A mathematical model for mechanotransduction at the early steps of suture formation

preprint, 43 pages (accepted Nov. 2012). Subject areas: evolution, theoretical biology, developmental biologyInternational audienceThe growth and the patterning of craniofacial sutures are subjected to the effects of mechanical stress. External constraints play a major role in the dynamics of bone deposition. Nevertheless, the mechanotransduction processes occuring at the margins of the sutures are not precisely understood. Here, we propose a simple theoretical model based on the orientation of collagen fibres within the suture in response to local stress. We demonstrate that fibre alignment generates an instability leading to the emergence of interdigitations. We confirm the appearance of this instability by analytical computations (dispersion relation) and by numerical simulations. In order to support our model, we use histology and synchrotron x-ray microtomography and reveal the fine structure of collagen fibres within the sutural mesenchyme and their insertion into the bone. These results strongly support the role of mechanical processes in the growth and patterning of craniofacial sutures and provide new directions for the understanding of normal and pathological suture fusion