Morphology of cryofixed myelin sheath.

The myelin sheath is formed by concentrically apposed membrane pairs and shows a regularly layered pattern of alternating light lines and dense lines. Observation of cryofixed myelin demonstrated that the structures represent aqueous spaces. All lamellae of the myelin sheath show globular aggregates of particles and these particles are corresponding with aggregates observed after detergent extraction of the myelin. Experimental fusion of myelin lamellae shows an intermixing of the globular particles or subunits. The interaction of these structural units in the bilayers may provide the stability of the myelin lamellae and their lamination.