CPM Seminar

Mechanics of in-vivo and in-vitro embryonic tissues

Karine Guevorkian

IGBMC Strasbourg

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 (AP) axis in vertebrate embryo, which takes place by addition of new cells into a mesenchymal tissue called the presomitic mesoderm (PSM), leading to the formation of the posterior organs. Unlike convergent-extension phenomena where the tissue deformation results from directed cell motion, the expansion of the PSM mainly takes place through a Brownian type 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.