In both vertebrates and invertebrates, postmitotic neurons are often generated by asymmetric divisions of neuronal progenitors such as neural stem cells. This general mechanism used to build the nervous system raises two important questions : how are these asymmetric divisions coordinated in space and how do the daughter cells acquire different fates. We address these questions using the nematode C. elegans as a model organism. In C. elegans embryos most neurons are generated during neurulation by asymmetric divisions oriented along the antero-posterior axis. We have recently shown that these terminal asymmetric divisions are regulated by a particular Wnt/β-catenin pathway. We are now trying to understand : 1) How the field of neuronal precursors is polarized. We address this question using advanced quantitative imaging techniques. 2) How the daughter cells acquire different fates and especially how the asymmetric division machinery is connected to the terminal differentiation program of postmitotic neurons. We analyze more specifically the role played by chromatin factors in this process.