Abnormal myelin maturation in vitro: the role of cerebrosides

Immunocytochemical demonstration of glial-neuronal interactions and myelinogenesis in subcultures of rat brain cells

Subcultures have been established from primary rat brain cell cultures and have been characterised with a range of cell-specific immunocytochemical markers. The subcultures are mainly composed of fibrous astrocytes, oligodendrocytes and neurones. The cells do not divide to any great extent giving a system where it is possible to follow culture development at the cellular level for a number of weeks. During this time oligodendrocytes colonise subpopulations of neurones, differentiate further showing the presence of myelin basic protein and elaborate myelin-like membrane; the fibrous astrocytes remain scattered uniformly throughout the cultures. Radially oriented processes emerge from the oligodendrocyte-neurone aggregates which subsequently coalesce to form fascicles that link the clusters of cells together. These fascicles react with antibodies for both neurofilament protein and myelin basic protein. The subcultures provide a straightforward system that is composed of cells derived entirely from the CNS, is free from mitotic inhibitors and yet retains a sufficiently low cell density to allow immunocytochemical identification of the cell types present. The subcultures should be useful for the study of trophic interactions between oligodendrocytes and neurones as well as the early events associated with myelinogenesis.

Myelin protein composition in the rat spinal cord in culture and in vivo: a developmental comparison

Biochemical characterization of the development of myelin in vitro was extended to an analysis of myelin protein composition in cultures of explanted foetal rat spinal cord. Myelin fractions were isolated from pooled explants after 12-30 days in vitro and, for comparison, from the spinal cords of rats of equivalent developmental ages. Electron microscopic examination of the culture myelin fractions revealed the presence of multilamellar myelin fragments and some single membranes. All fractions were analyzed using a micro-polyacrylamide gel electrophoresis technique. Qualitatively similar protein profiles were observed for myelin isolated from either cultures or from spinal cords. Fractions from cultures contained a greater proportion of high molecular weight proteins than those from spinal cords, although with respect to the 'major' myelin proteins, a quantitatively similar developmental pattern was observed both in vivo and in vitro.