NG2-Glia from Pallial Progenitors Produce the Largest Clonal Clusters of the Brain: Time Frame of Clonal Generation in Cortex and Olfactory Bulb

NG2-glia are the most unknown population originating in the CNS. Despite their relative abundance in the brain, fundamental questions about their function, heterogeneity, and origin remain in debate. Particularly, it is still intriguing how these cells escaped from classical in vivo clonal analyses describing other neural types. Using StarTrack labeling in mouse brains, we found that NG2-glia are produced as immense clonal clusters whose number of cells is about one order of magnitude higher than in other neural types. Unexpectedly, this number remained low during embryonic and early postnatal stages, increasing during adulthood. In addition, we also demonstrated a pallial origin of a telencephalic NG2 population, which in the olfactory bulb is derived from local progenitors. Together, our results reveal an original ontogenic process that gives rise to the NG2-glia population and expands the previously established limits of development.