Laboratoire Matière et Systèmes Complexes

Séminaire exceptionnel mercredi 9 mars à 15h, en salle 483A

Karine Guevorkian (IGBMC, Strasbourg)

Mechanics of axis elongation in chicken embryo

Morphogenesis is a fascinating process, which involves complex genetic pathways functioning in harmony with mechanical constraints to convert a mass of undifferentiated cells into an embryo. In our studies, we focus on the process of elongation of the anterior-posterior axis in vertebrate embryo, which leads to the development of the posterior organs in adults. The posterior part of the embryo consists of a mesenchymal tissue called the presomitic mesoderm, PSM, which governs the elongation process. Unlike convergent-extension phenomena where the tissue deformation results from directed cell motion, the expansion of the PSM rather takes place through Brownian cell movements. The physical mechanisms and the necessary conditions by which this specific type of cell movement results in a symmetry breaking event and therefore the elongation of the AP axis are yet not known. To address these questions, we use cell tracking to characterize the tissue flow along the AP axis of a chicken embryo and we study the changes in the elongation, as the cellular motility is modified. We will discuss how these experiments, along with rheological investigations of the PSM, help us further our understanding of the mechanics of axis elongation and the measurement of the elongation force inside the PSM.