The central nervous system continuously perceives, integrates, processes and generates information. These complex functions rely on the detailed elaboration of its cellular network and on the myriads of individual, highly differentiated and specialized cell types, classically subdivided into neurons, astrocytes and oligodendrocytes. The specification of these individual populations begins early during development with less differentiated, yet already partly restricted, progenitor cells. Anatomically located in dedicated germinative niches, neural progenitors perceive the influence of diffusible molecules of various natures and concentrations. These signals result in the initial specialization of cohorts of progenitors that express unique co...