Introduction: Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. Inflammation, demyelination and a variable degree of oligodendrocyte loss belong to the key features of this disorder.
Development: In MS plaques, different stages of demyelinating activity can be distinguished based on the presence of myelin proteins within the cytoplasm of macrophages, the degree of remyelination and the expression of macrophage activation antigens. Additionally, different patterns of oligodendrocyte loss and preservation can be found indicating a heterogenous pathogenesis of demyelination in MS. In the present report, we present criteria for classification of demyelinating activity as well as patterns of oligodendrocyte pathology.