The Formation Patterns of Central Myelin Sheaths in the Myelin Deficient Mutant Shiverer Mouse

Abstract

The myelin formation pattern of Shiverer mutant mice was investigated in detail by electron and light microscopy, especially with the Golgi silver-impregnation method. The myelin lamellae of Shiverer mice were mostly formed between stratified cytoplasmic sheets of oligodendroglia and their lamellae were only sporadically arranged in a spiral. We believe that some cytoplasmic sheets in these myelin sheaths might, even though in part, originate from plural processes either of the same or different oligodendroglia, and in addition, some cytoplasmic sheets might split to be multiplied in the number of stacked layers. Between these stratified cytoplasmic sheets incomplete compaction occurred to form a tri-lamellar membranous structure as we had described previously (Inoue et al.1981), in which the major dense lines were mostly absent.
We believe that the internodal segments of myelin sheaths might be much shorter than those of normal ones either by Golgi impregnated images or by electron microscopy, and might be more numerous in number than those of the control, although myelinated nerve fibers were remarkably less. Oligodendroglia proliferated predominantly in the Shiverer mouse spinal cord. Most of them were of the mature type with an electron-dense appearance.