<unk>  is a nonspecific reactive change of glial cells in response to damage to the central nervous system (CNS). In most cases,<unk>  involves the proliferation or hypertrophy of several different types of glial cells, including astrocytes, microglia, and oligodendrocytes. In its most extreme form, the proliferation associated with<unk>  leads to the formation of a glial scar. The process of<unk>  involves a series of cellular and molecular events that occur over several days. Typically, the first response to injury is the migration of macrophages and local microglia to the injury site. This process, which constitutes a form of<unk>  known as microgliosis, begins within hours of the initial CNS injury. Later, after 3–5 days, oligodendrocyte precursor cells are also recruited to the site and may contribute to remyelination. The final component of<unk>  is astrogliosis, the proliferation of surrounding astrocytes, which are the main constituents of the glial scar.<unk>  has historically been given a negative connotation due to its appearance in many CNS diseases and the inhibition of axonal regeneration caused by glial scar formation. However,<unk>  has been shown to have both beneficial and detrimental effects, and the balance between these is due to a complex array of factors and molecular signaling mechanisms, which affect the reaction of all glial cell types.
Gliosis
Glioma
Glioblastoma
Anaplastic astrocytoma
Hemangioblastoma
Gliosarcoma
Meningioma
Coma