Astrocytes are relatively large glial cells and have various functions, including accumulating in areas where neurons have been damaged. It is the most important histopathological sign of CNS injury. Astrocytes undergo both hypertrophy and hyperplasia. The nucleus enlarges and becomes vesicular and nucleolus becomes prominent. Previously scant cytoplasm expands and becomes bright pink and irregular from which arise numerous processes (gemistocytic astrocyte).
Bergmann gliosis is associated with anoxic injury and is characterized by death of Purkinje cells.
Gliosis and neuronal loss in certain brain regions are findings seen in various neurodegenerative disorders such as Alzheimer's disease, Korsakoff's syndrome, multiple system atrophy, prion disease, multiple sclerosis (after an acute attack) and AIDS dementia complex. It can also be found in Parkinson's disease.