Expression of the SMP antigen by oligodendrocytes in the developing avian central nervous system

Abstract

Expression of the avian antigen SMP (Schwann cell Myelin Protein, Mr 75-80000), first characterized in the PNS with a monoclonal antibody as an early and strictly specific Schwann cell marker, was further studied in the CNS. Comparing SMP immunoreactive areas in the different parts of the CNS with those expressing the Myelin Basic Protein (MBP), we showed a strict colocalisation of both phenotypes. In vitro, MBP+ oligodendrocytes express the surface antigen SMP as well. SMP cellular expression was followed in situ and in culture using nervous tissues from embryos at different stages. We were thus able to detect an early expression of this marker by oligodendroblasts before the first appearance of MBP immunoreactivity. We have also identified a subpopulation of SMP+/MBP- and SMP+/GC- cells, which persists under our culture conditions as precursors remaining in an immature state.