Gliosis refers scarring that occurs when the processes of fibrous astrocytes extend to cover and repair the damaged tissue; it is also called fibrillary gliosis. When the damaged tissue slowly and chronically progresses toward gliosis (as seen in degenerative disease), the astrocytic fiber components imitate the orientation of the original existing fibers and form a scar (gliosis). This is called isomorphic gliosis. In the event of relatively sudden tissue destruction, the astrocytic fibers progress in random directions and do not necessarily imitate the orientation of existing neural fibers. This is referred to as anisomorphic gliosis.