The neural stem cell niche of the embryonic and adult forebrain is rich in chondroitin sulfate glycosaminoglycans (CS-GAGs) that represent complex linear carbohydrate structures on the cell surface of neural stem/progenitor cells or in their intimate environment. We have reported earlier that the removal of CS-GAGs with the bacterial enzyme chondroitinase ABC (ChABC) reduced neural stem/progenitor cell proliferation and self-renewal, while this treatment favored astroglia formation at the expense of neurogenesis. Here, we studied the consequences of CS-deglycanation further and revealed that CS-GAGs are selectively required for neurosphere formation, proliferation and self-renewal of embryonic cortical neural stem/progenitor cells in response to FGF-2. Consistently, the FGF-2-dependent activation of the MAPKinase in neural stem/progenitor cells was diminished after ChABC treatment, but unaltered after EGF stimulation. Upon EGF-treatment, fewer radial glia were BLBP-positive while more were GLAST-positive after CS-GAG removal. Only in this latter situation, GLAST-positive radial glia cells extended processes that supported neuronal migration from differentiating neurospheres. CS-deglycanation also selectively increased astrocyte numbers and their migration in response to EGF. Thus, our approach revealed that CS-GAGs are essential for FGF-2-mediated proliferation and maintenance of neuron-generating neural stem/progenitor cells. Simultaneously, CS-GAGs act as a brake on the EGF-dependent maturation, migration and gliogenesis of neural stem/progenitor cells. We conclude that neural stem/progenitor cell subpopulations reside in neurospheres that are distinguishable by their responsiveness to FGF-2 and EGF that is differentially regulated by CS-carbohydrate structures.