We conclude that OPCs (and, to a lesser extent, COPs and NFOLs) may retain a memory of their anteroposterior position in the form of expression of region-specific transcription factors but that this does not translate into clearly distinct region-specific cell types. Thus, an initially diverse population of neural progenitors converges on a single intermediate transcriptional state (OPC or COP) and is then subject to secondary diversification as they mature (Figure 4E). Similar phenomena were recently reported in embryonic stem cells in vitro (Briggs et al., 2017) and, less dramatically, in the developing Drosophila brain (Li et al., 2017).
