The general context of our research addresses the following question: what are the cellular, molecular and mechanical mechanisms that link epithelial cell differentiation to morphogenesis? Our model is the cuboidal-to-squamous transition that occurs during the course of ovarian follicle development in Drosophila. This cell flattening depends on a genetic program that allow stereotyped adherens junction remodelling, on the pressure exerted by the growth of the underlying germline cells and on the stiffness of the surrounding basement membrane. We seek to identify the genes involved in cell shape changes and to determine the mechanical properties of the germline cells, the follicular cells and the basement membrane. To do so, we combine molecular tools, morphometry, and physical measurements to obtain an integrated view of morphogenesis.