Acute swelling is observed in the oligodendroglia with cerebral edema. Swelling-related degeneration develops more easily in oligodendroglia than in astrocytes.
Cerebral gray matter contains satellite oligodendroglia surrounding the neurons.
Mucoid degeneration refers to the accumulation of polysaccharides in the cell body as a result of degeneration.
The nuclei of oligodendroglia are often targeted by viral infections. In papovavirus (i.e., JC)-induced progressive multifocal leukoencephalopathy and measles virus-induced subacute sclerosing panencephalitis, extraneural viral inclusions form in the nuclei of oligodendroglia. The former present as swollen basophilic nuclei, whereas the latter appear eosinophilic with a thick distinct nuclear membrane.
GCIs are tadpole-like, eboshi-like (traditional Japanese noble head gear), argyrophilic inclusions that are formed in the cytoplasm of oligodenroglia in multiple system atrophy and are positive for ubiquitin and α-synuclein. GCIs are commonly formed in clinical diagnosis of olivopontocerebellar atrophy, striatonigral degeneration, or Shy–Drager syndrome. Therefore, MSA was proposed for the overall concept of the formation. GCIs are structures that created the epoch that gives this concept relevance.
As mentioned earlier, in neurodegenerative diseases accompanied by abnormal tau proteins, glial cells that involve abnormal phosphorylated tau deposits within astrocytes are observed. However, such deposits are also found in oligodendroglia and can be observed with GB and immunostaining.
In typical tauopathies such as PSP and CBD, Alzheimer’s disease, or other broader tauopathies, antiphospho-tau antibody- and GB-stained images of coiled bodies surrounding oligodendroglial nuclei can be observed and are called glial coiled bodies or coiled bodies. Other than their amount and distribution, these bodies do not specifically appear in tauopathies. Initially, glial coiled bodies were confused with GCIs, which had gained attention as a diagnostic marker for multiple system atrophy. However, they are essentially different in that the former are phosphorylated tau positive, whereas the latter are negative.
In tauopathy, the processes and not the cytoplasm of oligodendroglia develop abnormal phosphorylated tau deposits, which appear like curly threads with GB staining and immunostaining. These so-called argyrophilic threads are relatively common in PSP and CBD; however, they morphologically differ between the two diseases.