From Big Medical Encyclopedia

ADENOID TISSUE (Latin lympha pure water, moisture + grech, eidos look; synonym lymphatic fabric) — the morfofunktsionalny complex of lymphocytes and macrophages which is located in a cellular and fibrous connective tissue basis and making the functioning parenchyma of lymphoid bodies; L. t. it is inseparably linked with hemopoietic fabric.

Carry to the lymphoid bodies which are bodies of an immunogenesis thymus (see), lymph nodes (see), spleen (see), lymphoid elements marrow (see) and accumulations of an adenoid tissue on the course went. - kish. path. Lymphoid bodies concerning function of an immunogenesis divide on primary and secondary. So, a thymus carry to the central bodies of system of an immunogenesis (formation of cellular system of immunity), and a white pulp of a spleen, limf, nodes and accumulations of L. t. in a mucous membrane of a digestive tract — to secondary, or peripheral, to bodies of an immunogenesis.

Main stages of evolution of L. t. are rather outlined. At backboneless L. t. no. The predecessor of a thymus having an appearance of small lymphoid accumulations in an epithelium of a peripharyngeal groove for the first time is found in cyclostomous (lampreys). At these animals ability to an immune response as reaction of hypersensitivity of the slowed-down type and reaction of rejection of allotransplant is established. The spleen, L is found in primitive cartilaginous fishes. t. in intestines, kidneys, gonads, in perivascular connecting fabric. Sturgeon fishes have plasmocytes, i.e. ability to development of specific antibodies. Amphibians and reptiles differ in emergence of red marrow, the centers of a lymphoid hemopoiesis in a liver. Birds along with concentration of lymphoid elements in the field of kloakalny body — a bursa of Fabricius — have rudimentary limf, nodes (see. Lymphatic system ).

All lymphoid bodies of mammals, including and the person, consist of the connective tissue basis presented by collagenic and argyrophil fibers, in to-rykh constant (stable) cellular elements L are located. t. and continuously other cells migrate. Basic cellular elements L. t. are lymphocytes (see), macrophages (see), plasmocytes (see), fibroblasts, endothelial and reticular macrophages. The lymphocytes and their derivatives entering so-called lymphoid system, and system of macrophages, lying in fibroretikulyarny fabric make a basis of L. t. (so-called macrophagic and phagocytal system). In 1970 R. van Furth and soavt, offered given funkts, system to call limforetikulogistiotsitarny system.

The reticular macrophages forming reticular fibers on morphology (at the level of light microscopy) do not differ from fibroblasts connecting fabric (see). Sovr, researches on a histogenesis of the hemopoietic fabric resulted in need of review of ideas of a reticular macrophage. Various authors consider it differently. A. Ya. Fridenstein and K. S. Lalykina (1973) believe that reticular macrophages of a stroma of secondary lymphoid bodies (mekhanotsita) are formed of the special stem cells different from stem cells of blood. Reticular macrophages of different bodies, despite morfol, similarity, differ on an orientation of a differentiation: reticular macrophages of cultures of marrow at the return change in an organism form a bone, and of cultures of a spleen — reticular fibers. I. N. Kokorin (1970) and soavt, consider that reticular macrophages of a spleen are polipotentny stromal cells of this body. It is possible to assume that reticular macrophages combine several types of cells: the histiocytes corresponding to macrophages, monocytes, fibroblasts, and also so-called dentritic and interdigitiruyushchy cells.

In 1927 A. A. Maximov, criticizing the concept reticuloendothelial system (see), pointed out distinctions in an origin, morphology and function of endothelial cells of vessels and reticular macrophages. Then presence of different predecessors of these cells was established and distinctions are confirmed them funkts. It is shown that endotheliocytes of vessels, fibroblasts and reticular macrophages belong to slabofagotsitiruyushchy elements: coloring at introduction of a vital stain (especially in high doses) results from them generally pinocytic (see), but not phagocytosis. It turned out that macrophages of a liver (kupferovsky cells) and macrophages of a red pulp of a spleen, but not endotheliocytes and not reticular macrophages participate in clearance of blood preferential.

For designation of morfofunktsionalny system of various cells of the lymphoid and plasmatic ranks participating in processes of an immunogenesis, a number of authors applied the term «lymphoid and macrophagic system» earlier. This term lymphocytes, monocytes, so-called polyblasts, macrophages of inflammatory exudate, and also plasmocytes — direct producers of antibodies combined in a uniform funkts, system.

Steady level of process fiziol. regenerations in primary lymphoid human organs is established at the end of the embryonal period, in secondary — in the early post-natal period.

In the course of functioning there is a disintegration and death of lymphoid cells and elements of a stroma, their number is continuously compensated by proliferation, a differentiation and migration of cells.

Age changes in a thymus, the maximum weight are most demonstrative the cut (30 — 40 g) falls on the pubertal period, then it quickly is exposed to involution; increase of number of labrocytes (mast cells) is noted, the quantity of plasmocytes at first increases, then they disappear, the quantity of epithelial cells decreases; there is fatty substitution of a parenchyma. Quite often after 30 years only microscopic examination allows to find small accumulations of the lymphocytes and epithelial cells put in a fatty or fibrous basis in a thymus.

Changes in lymphoid bodies at elderly people serve as reflection of reduced immune responsiveness.

The factors regulating processes fiziol and reparative regeneration in primary and secondary lymphoid bodies, are found out partially: somatotropic hormone, a calcitonin, vasopressin and other hormones strengthen proliferation of cells of primary lymphoid bodies, hormones of cortical substance of adrenal glands suppress a lymphocytopoiesis in a spleen and limf, nodes; in an experiment passive introduction of antibodies slows down proliferation of cells at effect of antigen. The humoral factor (Timosinum) developed by a thymus, promoting proliferation of thymocytes and formation of O-antigens on a surface of the stem cells of marrow migrating in a thymus is established. However the factor influencing a lymphocytopoiesis is finally not revealed (see. Leykopoetina ). The factors causing growth of a thymus in the post-natal period and its involution at adult organisms are not clear. At the same time it is established that direct contact with extremely peculiar retikuloepitelialny stroma of a thymus is necessary for maturing of thymocytes. A. Ya. Fridenstein (1973) suggested that distinctions in the response to the damaging influence of primary and secondary lymphoid bodies can be connected with a difference in character and an origin of their stroma. T. A. Rozhnova (1971), to Borons (To. Borum, 1969) experimentally established that reparative regeneration in a thymus happens only when the damaging influence (radiation, a kortizonoterapiya, a resection, etc.) significantly does not break an integrity of a stroma. At the same time in a thymus lymphoid cells of marrow, due to proliferation migrate to-rykh and there is a regeneration of body, however its weight does not reach a normal amount any more.

Reparative regeneration of secondary lymphoid bodies (a spleen and limf, nodes) is caused not only proliferation of repopuliruyushchy cells from marrow and a thymus, but also reproduction of the remained cells of bodies. G. V. Harlova (1975) assumes that the speed and completeness of regeneration of secondary lymphoid body depend on a ratio and maturing of T in it - and V-lymphocytes. It is shown that lymphocytes take part in regenerative processes not only in lymphoid bodies, but also in a liver, lungs, skin, kidneys.

Funkts, value L. t. is defined by its major role in immune responses. Process of development of antibodies is carried out by cells of L. t. Quite reasonable assumption expresses that T - and V-lymphocytes by a feed-back can control an immune response and division of stem cells. Nek-ry researchers believe that loss of ability of T lymphocytes to such control can be the reason of autoimmune diseases, and also is one of possible conditions of development of a malignant new growth.

Defense reaction of an organism (ekzo-and endogenous) considerably is defined on influence of alien substances funkts, a condition of L. t., about a cut specific (immunological) resistance is connected (see. Immunity ). There are proofs of great value of L. t. not only in immune responses, but also in nonspecific resistance of an organism (see). As showed P. D. Gorizontov (1976) researches, increase in resistance of an organism at a stress is characterized by strengthening of a marrowy blood formation, increase in migration of cells of L. t. in marrow during the first hours after influence of an extraordinary irritant — so-called lymphoid peak. Emergence at the same time of T lymphocytes in marrow is considered by researchers as the certificate of a role of a thymus in nonspecific resistance of an organism.

It is supposed that at adverse effects disintegration of cells of L. t. provides trophic function since at the same time products of exchange (in particular, nucleoproteids) reutilizirutsya in zones of damage of fabrics, than an adverse effect is compensated. Burns (D. W. Bernes, 1962) and soavt, expressed opinion that insufficiency of L. t. and reduction of its trophic function play an important pathogenetic role at so-called diseases of exhaustion, including and at the wound exhaustion described by I. V. Davydovsky.

The diseases connected with defeat of L. t., are usually diagnosed according to biopsies limf, nodes (except for leukoses, dysgammaglobulinemias and autoimmune processes). To diseases of L. t. belong a hypoplasia limf, nodes — the rare state reflecting immune insufficiency; a reactive hyperplasia limf, nodes, arising at inflammatory processes and activation of immune responses of both primary, and secondary character (see. Immunomorphology , Immunopathology ). The solution of a question of character of a so-called inflammatory component (emergence of eosinophils, neutrophils, plasmatic and epithelial cells) quite often presents considerable difficulties.

Special group patol, processes of L. t. make malignant new growths (see. Hemoblastoses , Histiocytoses , Lymphogranulomatosis , Lymphoma , Multiple myeloma ).

See also Reticular fabric .

Bibliography: P. D horizons. Adenoid tissue and nonspecific resistance of an organism, Arkh. patol., t. 38, No. 3, page 3, 1976, bibliogr.; Pestova I. M. A short sketch of evolution of an adenoid tissue and its immunocellular reactivity at vertebrata, Arkh. annate., gistol, and embriol., t. 70, No. 3, page 26, 1976, bibliogr.; Structure and function of an adenoid tissue in onto-and phylogenesis, under the editorship of E. A. Wagner, etc., Perm, 1976; Harlova G. V. Regeneration of lymphoid bodies at mammals, M., 1975, bibliogr.; Sagas of J. The line structure of the mammalian lymphoreticular system, Int. Rev. Cytol., y. 27, p. 283, 1970, bibliogr.; it, The macrophage — a review of ultrastructure and function, L. — N. Y., 1973; G o 1 d s t e i n A. L., Slater F. D. a. White A. Preparation, assay and partial purification of thymic lymphocytopoietic factor (thymosin), Proc, nat. Acad. Sci. (Wash.), v. 56, p. 1010, 1966; Kyriazis A. A. a. Ester-1 y J. R. Fetal and neonatal development of lymphoid tissues, Arch. Path., v. 91, p. 444, 1971; M a x i m o w A. Bindegewebe und blutbildene Gewebe, Handb, mikr. Anat. Menschen, hrsg. v. W. Mollendorff, Bd 2, T. 1, S. 232, B. 1927; Mononuclear phagocytes m immunity, infection and pathology, ed. by R. van Furth, Oxford, 1975.

G. A. Frank.