Schwann cells are the myelinating glia of the PNS and differ from CNS oligodendrocytes by expressing myelin components Pmp22 and Mpz, the tetraspanin Cd9, and the extracellular matrix calcium-binding osteonectin Sparc and by not expressing the tight junction Cldn11, the myelin protein Mobp, Mog, and the iron chelator Trf genes (Figure S3C).
