TIGROLYSIS

TIGROLYSIS (syn. chromolysis, chromatolysis), a pathological process in the nerve cell, characterized by the disintegration, dissolution, or complete disappearance of Nissl substance or tigroid substance from the cell. When tigrolysis is present, the cell is stained diffusely or remains unstained with special cellular staining methods. Tigrolysis may be complete or partial. Complete tigrolysis occurs when all Nissl substance is affected, and partial when in one part of the cell—around the nucleus, at the periphery, or in one half of the cell—the grains retain their normal appearance, while in other parts of the same cell they dissolve. For the most part, tigrolysis is accompanied by other changes in the cell—swelling, displacement of the nucleus to the periphery, appearance of pigment and vacuoles, wrinkling of the cell and its atrophy. Tigrolysis is observed in all cells of the central nervous system (spinal cord, brain stem, brain), as well as in spinal and autonomic ganglia, in various pathological processes: inflammatory (poliomyelitis, encephalitis, polioencephalitis), degenerative (amyotrophic lateral sclerosis, etc.), in intoxications, in changes in cell nutrition (anemia), in excessive physical fatigue (experiments on animals). Violation of the integrity of the axis cylinders also leads to tigrolysis in the cells that give rise to these fibers; this forms the basis for the method of chromolytic reaction used in experimental medicine to determine the connection of a severed nerve with the corresponding group of cells (that group of cells in which tigrolysis has occurred will be the nucleus of the given nerve). After severing the nerve, tigrolysis appears in the cell on the second day, reaching its maximum after 12-14 days; in other pathological processes, tigrolysis depends on the intensity of the process. With the disappearance of the pathological factor, if the cells have not yet completely died, restoration of the Nissl substance may occur.