Virus-induced demyelination in mice: "dying back" of oligodendrocytes.

Demyelination was produced in mice by intracerebral inoculation of Theiler's murine encephalomyelitis virus. The earliest ultrastructural changes occurred in the inner cytoplasmic tongues of oligodendrocytes, the most distal extension of these cells. Viral antigen was localized to glial loops that connect with myelin lamellae. This study indicates that a "dying-back" process may occur in virus-infected oligodendrocytes, which then results in demyelination.