Fig. 4.

Origins of cortical oligodendrocytes in the spinal cord (a) and brain (b). a There are at least two sources of OL-lineage cell generation in the embryonic spinal cord: the pMN domain and more dorsal region. Oligodendrogenesis from the pMN domain is dependent on Shh and disrupted in Shh-deficient mice, whereas dorsal oligodendrogenesis remains in such mice. b A revised model of oligodendrogenesis in the forebrain showing that three sequential waves of OPC generation from neural precursors in different regions: the Nkx2.1⁺ medial ganglionic eminence (MGE) starting at E12.5, the Gsh2⁺ lateral-to-caudal GE starting at E15.5, and the Emx1⁺ cortical ventricular zone starting around birth