My objective is to understand how localized cortical actin/myosin contractility in individual cells within the Drosophila wing hinge and wing blade combine to generate the epithelial remodelling and convergence-extension movements that occur throughout the tissue. In particular, I will examine the role of the planar cell polarity proteins in generating and/or responding to these forces and test the hypothesis that convergence-extension movements are driven by external stretching forces caused by hinge contraction. To do so, I will use a multidisciplinary approach, including both genetics and biophysics. I will combine the genetic tools of Drosophila, to manipulate gene activity in time and space, with long-term time lapse imaging and automated image analysis, developed only recently in the Eaton lab, to quantitatively describe the effects of genetically induced cortical perturbations on cell behaviour. I will myself develop a completely novel method to exert controllable forces on wing tissue in vivo by directing the production of magnetic nanoparticles in specific regions of the wing. The originality of this project lies not only in its conceptual novelty, but in the powerful combination these methods and physical modelling that will be exploited to address the problem.