Epithelial-Mesenchymal Transition (EMT) is a complex process converting epithelial tissues into loose cell collectives endowed with migratory capabilities. One of the main outcomes of EMT is extrusion of mesenchymal cells from an epithelial tissue toward the basal compartment. There, cells can engage with the extracellular matrix and migrate away from their site of origin. Thus, EMT is a central process in early embryonic development, allowing cells to reorganize to form the various structures of the body plan, but also promotes dissemination of tumor cells. EMT is performed through a series of non-compulsory steps, does not systematically reach full mesenchymalization and is reversible. In addition, cell populations undergoing EMT often display heterogeneous expression of genes essential for the process. Further, a diversity of cell behaviors has been observed during EMT. The impact of these heterogeneities in gene expressions and cell behaviors on the dynamics and the efficiency of EMT is not known. In the lab, we try to address these knowledge gaps by studying an embryonic stem cell population called the Neural Crest. These cells are generated from the dorsal neuroepithelium by EMT and represent an excellent in vivo model system to study the dynamics of EMT. However, there are several technical limitations that one encounters while working in living systems. To bypass some of these hurdles, we used computational modelling to probe the theoretical impact of the main EMT events on the overall dynamics and efficiency of EMT, in the hope that these in silico findings would improve our understanding of the process, raise new hypotheses and help us design further experimental approaches. During the workshop, I will present the current views on EMT and the dichotomy between these views and some biological observations. I will present our experimental system, explain the pending questions and technical hurdles and discuss how the modelling actively helped us rethink what is deemed important for EMT to generate basal extrusion of cells.