An olig2 reporter gene marks oligodendrocyte precursors in the postembryonic spinal cord of zebrafish

Continuous production of new neurons and glia in adult mammals occurs within specialized proliferation zones of the forebrain. Neural cell proliferation and neurogenesis is more widespread in adult amphibians, reptiles, and fish but the identity of neural stem cell populations in these organisms has not been fully described. We investigated expression of a reporter gene driven by olig2 regulatory DNA at postembryonic stages in zebrafish. We show that olig2 expression marks a discrete population of spinal cord radial glia in larvae and adults that divide continuously. olig²⁺ radial glia have hallmarks of stem cells and their divisions appear to be asymmetric, producing new oligodendrocytes but not neurons or astrocytes.