Genetic Evidence that Dorsal Spinal Oligodendrocyte Progenitor Cells are Capable of Myelinating Ventral Axons Effectively in Mice

In the developing spinal cord,the majority of oligodendrocyte progenitor cells(OPCs)are induced in the ventral neuroepithelium under the control of the Sonic Hedgehog(Shh)signaling pathway,whereas a small subset of OPCs are generated from the dorsal neuroepithelial cells independent of the Shh pathway.Although dors allyderived OPCs(dOPCs)have been shown to participate in local axonal myelination in the dorsolateral regions during development,it is not known whether they are capable of migrating into the ventral region and myelinating ventral axons.In this study,we confirmed and extended the previous study on the developmental potential of dOPCs in the absence of ventrally-derived OPCs(vOPCs).In NestinSmo conditional knockout(cKO)mice,when ventral oligodendrogenesis was blocked,dOPCs were found to undergo rapid amplification,spread to ventral spinal tissue,and eventually differentiated into myelinating OLs in the ventral white matter with a temporal delay,providing genetic evidence that dOPCs are capable of myelinating ventral axons in the mouse spinal cord.