Difference in the response to extracellularly applied pathological α-syn between two oligodendroglial cells. Pathological α-syn with seeding property hypothetically propagates from OLG to OLG. Extracellular α-syn fibrils do not induce inclusions when they are applied to mature OLGs. Seed internalization can occur more drastically during the immature state of OLG differentiation including the precursor state. The mechanism which regulates the uptake of misfolded α-syn may be shared by normal OPCs and pathological OLGs in MSA brains, but not by normal OLGs. a: intercellular localization of α-syn (green)-immunoreactive inclusions in platelet-derived growth factor receptor α (red)-positive primary rat OPCs, which were incubated for 72 h with 1 μM human recombinant α-syn pre-formed fibrils (PFFs). b: MBP (red)-positive primary rat OLGs with extracellular Thioflavin S (green) immunoreactivity, which were incubated for 24 h with 1 μM human recombinant α-syn PFFs after maturation. c: MBP (red)-positive primary rat OLGs containing Thioflavin S (green)-positive intracellular inclusions. OLGs were differentiated from OPCs that were pre-incubated for 24 h with 1 μM human recombinant α-syn PFFs. a-c: Each scale bar represents 10 μm. Blue; DAPI.