Oligodendrocytes can be generated from the local ventricular and subventricular zones of embryonic chicken midbrain

It is well established that early oligodendrocyte progenitors (OLPs) are induced by Sonic hedgehog (Shh) from the ventral ventricular zone throughout the entire neural axis. Here, we report that OLP cells can also be generated from the dorsal ventricular and subventricular zone in embryonic chicken midbrain at later stages. Concomitantly, a low level of Shh expression is detected in the adjacent ventricular and subventricular zones, implying that oligodendrogenesis in the dorsal midbrain is also regulated by Shh. In addition, Nkx2.2 and Olig2 are co-expressed in the same OLPs generated from the dorsal midbrain, suggesting that the dorsal oligodendrogenesis is similarly under the dual control of these two transcription factors as in the developing spinal cord.