Adult neural stem cells (NSCs) hold great potential for the treatment of neurodegenerative diseases and nervous system injuries. To date, adult neurogenesis has been mainly studied in rodents but, on p. 1459, Laure Bally-Cuif and co-workers use GFP-encoding viruses and clonal analyses to characterise NSCs in the adult zebrafish brain. Zebrafish grow throughout life and maintain germinal centres in the brain that continually add new cells to the nervous system. The telencephalic germinal zone contains quiescent radial glial progenitors and actively dividing neuroblasts and the researchers now show that these progenitors have different division modes and fates. Thus, neuroblasts primarily undergo a limited amplification phase followed by symmetric neurogenic divisions, whereas radial glia self-renew and generate different cell types, a result that identifies them as bona fide NSCs. Importantly, the researchers also show that most radial glia divide symmetrically, which amplifies and maintains the NSC pool. These and other results establish zebrafish as an important model system for studying adult neurogenesis.
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