Activation of Wnt/β-catenin signaling inhibits the generation of OLPs. Transverse sections of spinal cord from E13.5 (a–a′, d–d′), E16.5 (b–b′, e–e′), and E18.5 (c–c′, f–f′) of WT (a–f) and CatG/+ (a′–f′) mice are subjected to ISH with Sox10 and Pdgfrα riboprobes. Lack of expression of Sox10 and Pdgfrα in the spinal cord of CatG/+ mice (b′–f′) indicated that specification of OLPs from neural stem cells was impaired.