Electron Microscopic Study on Nuclear Changes in Multiple Sclerosis Brain Biopsies

Since intranuclear and cytoplasmic inclusions are characteristic features of virus infections, including SSPE, a biopsy analysis was made from ten MS cases in order to find out those changes suggesting possible viral particles and other signs of infected cells. In three acute cases intranuclear inclusions were found in astrocytes and oligodendrocytes. The majority of these inclusions consisted of small granules about 200 Å in diameter and the total diameter of the inclusions varied from 0.1 to 0.3 microns. Finely granular intranuclear inclusions were also infrequently found. Furthermore nuclear envelope often displayed abnormalities in the same cells which contained nuclear inclusions. Intracytoplasmic inclusions or giant cells were not found nor were clear-cut virus particles. These findings show that nuclear inclusions are characteristic of some acute MS cases. Further studies are necessary in order to relate these inclusions to possible viral etiology of MS.