MULTIPLE-SCLEROSIS - OLIGODENDROCYTE SURVIVAL AND PROLIFERATION IN AN ACTIVE ESTABLISHED LESION

Abstract

Oligodendrocytes were studied ultrastructurally in relationship to areas of active demyelination in multiple sclerosis. The [human] tissue came from a CNS plaque sampled at biopsy during a neurosurgical procedure to correct severe intention tremor in a case of chronic progressive multiple sclerosis. Cells interpreted as oligodendrocytes were abundant within the demyelinated zone, were easily identifiable and sometimes occurred as nests of cells suggestive of proliferation. Oligodendrocytes were also common within areas of active demyelination where numerous macrophages displayed active phagocytosis of myelin. These oligodendrocytes were paler and perhaps represented residual, surviving cells. In the relatively normal white matter adjacent to the plaque, increased numbers of oligodendrocytes occurred in association with remyelination. In the demyelinated zone, the astrocyte:macrophage:oligodendrocyte ratio was 1:2.25:4.5; within the region of ongoing demyelination, 1:4:4; and in the adjacent white matter, 1:0.1:2.1. There evidently is no selective depletion of oligodendrocytes either during or shortly following CNS demyelination in multiple sclerosis, and that the myelin sheath is the primary target.