From Big Medical Encyclopedia

SYNOVIAL MEMBRANE [membrana synovialis (PNA); stratum synoviale (JNA, BNA); synonym synovial membrane] — the layer of specifically organized connecting fabric covering a joint cavity and also cavities of synovial bags and synovial vaginas of sinews. The village of the lake forms synovial folds (plicae syno-viales) and synovial vorsina (villi synoviales) turned into a joint cavity. The village of the lake consists of cells, fibers, the main substance and supports circulatory and absorbent vessels, nerve fibrils and the terminations.

In S. islands distinguish three layers: the cover, covering synovial cavity, and two fibrous — superficial collagenic and elastic, subject cover, and deep collagenic and elastic, interwoven into a fibrous cover. Under nek-ry sites of a deep collagenic and elastic layer there are considerable accumulations of fatty tissue.

The covering layer of S. of the lake unlike an endothelium of vessels or a mesothelium of the serous covers which are a single-layer cellular vystilka represents specifically differentiated superficial part C. of the lake. Superficially located cells — sinoviotsita, the main substance, and also circulatory capillaries, nerve fibrils and the terminations are a part of a covering layer.

Sinoviotsita are located at the different levels in relation to a surface of a synovial membrane since the basal membrane is absent, and the main substance along with sinoviotsita limits a joint cavity.

Fig. 1. Microdrugs of a synovial membrane of a knee joint: and — the arranged bunches of collagenic fibers in a surface fibrous layer (plane drug; coloring by aniline blue; x 200); — network of elastic fibers in a deep fibrous layer (coloring by orcein; X 200); in — network of blood vessels (plane drug; fruit liqueur of vessels Berlin blue on gelatin; X140).

Fibrous layers unlike friable connecting fabric (see) have accurately arranged bunches of collagenic and elastic fibers, the direction to-rykh in a surface fibrous layer matches the main vectors of shift of a cover at the movements (fig. 1, a), in deep (fig. 1,6) — fibers are interwoven into a fibrous cover, providing S.'s fixing by the lake, and also preservation of a configuration and volume of a joint cavity.

Among the sinoviotsit which are an organospetsifichesky kind of cells of a fibroblastichesky row distinguish macrophagic sinoviotsita (A-cells) producing enzymes and capable to phagocytosis, fibroblastichesky sinoviotsita (V-cells) producing hyaluronic to - that (see. Hyaluronic acids ) — a specific component of synovial fluid, and intermediate forms of sinoviotsit (S-cell), being, apparently, predecessors And - and V-cells. Besides, in cover and fibrous layers of S. of the lake there are always fabric macrophages (see), fibroblasts, plasmocytes (see), mast cells (see), mononuclear cells blood (see), to-rye in total provide immune and barrier function C. of the lake. Fabric macrophages and macrophagic sinoviotsita also take part in preparation of krupnomolekulyarny particles and cells for removal from a joint cavity. The active role in it belongs to lizosomalny enzymes of these cells.

Fig. 2. The diagrammatic representation of a gematosinovialny barrier and possible ways of circulation of substances through it (are specified by shooters): 1 — a gleam of a joint cavity; 2 — sinoviotsit; 3 — the main substance of a covering layer; 4 — an endotheliocyte; 5 — a gleam of a circulatory capillary; 6 — a chain of vesicles in cytoplasm of an endotelnotsit; 7 — area of contact of endotheliocytes; 8 — the fenestrirovanny site in an endothelium of a capillary.

The village of the lake it is rich with blood vessels (fig. 1, c), to-rye get from the subject fabrics and distributed in its thickness, including also a covering layer. The joint cavity is separated from a circulatory bed only by cells and the main substance of a covering layer of S. the lake and a wall of a capillary. In total they form a gematosinovialny barrier, through to-ry exchange processes between a circulatory bed and a joint cavity are carried out. There are three main ways of transcapillary transport: through fenestrirovanny sites of an endothelium, through cytoplasm of endotheliocytes by education and movement of a chain of vesicles, and also through the main substance in a zone of contact of endotheliocytes. Between a covering layer and a joint cavity exchange processes are carried out through cytoplasm of sinoviotsit or the main substance (fig. 2). From a circulatory bed electrolytes and proteins with low molecular weight, including enzymes normal get into a joint cavity. From a joint cavity in blood crystalloid solutions are soaked up very intensively, colloid — much more slowly and in direct dependence on the size of molecules of a colloid (the colloid particles close by the sizes to a molecule of globulin, through a gematosinovialny barrier do not get, and are removed through limf, a bed).

Limf, capillaries are located in fibrous layers of S. of the lake up to a covering layer. The total area limf, beds exceeds that of a circulatory bed almost twice. There is an opinion that ways of transport of metabolites for an endothelium limf, capillaries the same, as for an endothelium of a wall of circulatory capillaries. Limf, a bed possesses the expressed drainage function; through limf, a bed the water, proteins, colloid particles and cells which underwent a preliminary lysis are removed from a joint cavity.

The village of the lake is innervated, as well as other structures of a joint, the mixed spinal nerves bearing sympathetic fibers in the structure.

Morphological and functional community of such components of a joint as synovial membrane, synovial fluid (see) and a joint cartilage, allowed to allocate the concept «synovial environment of a joint».

At various diseases, damages and tumoral processes joints (see), synovial bags (see) and tendinous vaginas (see. Synovial vaginas of sinews ) The village of the lake can be involved in patol. process (see. Arthritises , Bursitis , Synovioma , Synovitis , Tendovaginitis ).

See also articles devoted to individual diseases at to-rykh joints are involved in process, e.g. Rheumatism , Pseudorheumatism , Reuters disease etc.

Bibliography: Pavlova V. N. Synovial environment of joints, M., 1980, bibliogr.; H a m e r m a n D. and. In and - 1 a n d P. Structure and function of the synovial membrane, Bull, rheum. Dis., v. 16, p. 396, 1966, bibliogr.; W a s s i-1 e v W. Elektronemikroskopische und histochemische Untersuchungen zur Ent-wicklung des Kniegelenkes der Ratte, Z. Anat. Entwickl. - Gesch., Bd 137, S. 221, 1972.

Century of H. Pavlova.