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.