During development, specific cellular and molecular programs orchestrate the differentiation of the various cell types that make up our body. This includes the acquisition of specific cell morphologies that in turn enable particular cellular and physiological functions. Epithelial cells and neurons are two striking examples of cell types whose differentiation is based on the acquisition of a highly specialized morphology that in both cases includes the elaboration of polarized features. During development, epithelial cells have to evolve an apico-basal axis of polarity as well as discrete cell-cell contacts, thus enabling organogenesis. Neurons are also highly polarized cells and have to differentiate their dendrites from the axon in order to enable neural circuit formation. Defective epithelial polarity is a hallmark of cancer and is thought to be a precursor of cells metastasis. Polarity defects during neuron migration and differentiation are thought to be contributing factors toward a number neurodevelopmental conditions. There is therefore a strong impetus to elucidate the cellular and molecular basis for epithelial and neuronal differentiation and morphogenesis during development, as well as how these cells are maintained through adulthood. To address these issues, our group is using the genetically amenable Drosophila melanogaster combined with various in vitro culture systems.