Survival and mitosis of myelinating oligodendrocytes in experimental autoimmune encephalomyelitis: an immunocytochemical study with Rip antibody

The fate of myelin-forming oligodendrocytes in the spinal cord of Lewis rat s with acute and chronic relapsing experimental autoimmune encephalomyeliti s (EAE) was studied using the pre-embedding immunolabelling technique with the Rip monoclonal antibody which specifically labels the cytoplasm of the cell body and processes of the mature oligodendrocyte. Morphologically norm al Rip-positive (Rip(+)) cells were found in close contact with demyelinate d axons at the onset of demyelination and during the course of disease, ind icating that oligodendrocytes survive the acute demyelinating insult. Occas ional Rip(+) oligodendrocytes were undergoing mitosis at the time of onset of neurological signs. These mitotic oligodendrocytes were present in both the grey and white matter. The majority of the mitotic oligodendrocytes had processes in direct contact with myelin sheaths for considerable lengths, indicating that they were myelinating cells. This study indicates that olig odendrocytes survive the acute demyelinating insult in EAE and that mature myelinating oligodendrocytes are able to undergo mitosis.