GLIOSIS (gliosis; glue Greek glia + - osis) — growth of an astrocytic glia with products of gliozny fibers in a head or spinal cord. Proliferation of other types of a glia (a microglia, an oligodendrogliya) the term «gliosis» is usually not designated, except a so-called miyelinizatsionny gliosis, meaning by this term reproduction of various forms of an oligodendrogliya in the course of myelination of nerve fibrils.
— rather private patol, process at chronically proceeding focal or diffuse defeats of c. N of page. It is one of stages of formation of a brain hem. For hron, meningoentsefalit the subshell marginal and subependimalny G., are characteristic of multiple sclerosis — focal G. of white matter in a zone of an arrangement of the plaques typical for this disease, of epilepsy — G. of a hippocampus which usually is followed by wrinkling and consolidation of its crinkles. Often also perivascular G. meets, at Krom growth of an astrocytic glia and gliozny fibers happens around the inflamed or sclerosed vessels, napr, at vasculites, a hypoxia, perivascular encephalitis.
Represents process of a replaceable hyperplasia of an astrocytic glia in response to slowly proceeding death of nervous tissue. Can be a source of development of true tumors — astrocyte (see). Cases of a combination of focal G. with the gliomas developing in another, not struck with G. departments of c are described. N of page.
Macroscopically It is expressed in bigger or smaller consolidation of tissue of brain. If G. develops in gray matter of bark as, e.g., at tuberous sclerosis (see), affected areas gain white color, and separate crinkles have cartilaginous density. At G. of white matter of hemispheres, napr, at a diffusion sclerosis, color of affected areas can be various (grayish, yellowish, pink) that depends on the accompanying G. patol, processes (demyelination, a plethora of vascular network), but it almost always differs from color of the neighboring healthy sites of a brain.
Microscopic changes at G. are expressed in growth fibrilloobrazuyushchy and (in smaller number) protoplasmatic astrocytes (gliozny proliferation) is frequent with considerable products of gliozny fibers which can form the rough intertwining bunches and curls or nezhnopetlisty networks. The is longer G. proceeds, the gliozny fibers less cellular elements (fibrous G.) appear more. G.'s differentiation and a gliomatosis microscopically is not always possible. At the same time emergence in the centers of a gliomatosis atipichesky (so-called monstrozny) astrocytes, and also polyploid forms of astrocytes which, however, do not find figures of mitotic division matters; this type of astrocytes is characterized by voluminous cytoplasm and fabiform, and sometimes and the segmented kernel.
At rather correct arrangement of gliozny fibers which is not breaking the general structure of this site of brain fabric it is accepted to speak about isomorphic G. contrary to anizomorfny G. at which gliozny fibers are located chaotically. Anizomorfny glioses are usually combined with considerable deformation and even death of affected areas of c. N of page, as, e.g., at myelosyringoses (see), effects of an injury and disturbances of cerebral circulation at early children's age etc. In G.'s centers coarsening of brain vessels is almost constantly observed, it is frequent with a hyalinosis of a wall or an obliteration of a gleam.
See also Neuroglia .
A. P. Avtsyn.