THYMUS

From Big Medical Encyclopedia

THYMUS (thymus; synonym: thymus gland, goitrous gland) — the pair lobular body located in an upper part of a front mediastinum; is the central body of system of an immunogenesis responsible for formation and functioning of cellular system of immunity.

Long time of Century. attributed the most various functions, including influence on growth and sexual development, a metabolism, etc. And only since the 60th years after it was proved that removal of Century. before formation of peripheral lymphoid bodies (a spleen, limf, nodes) leads to abortion of all system of an immunogenesis and to inability to carry out immune responses [I. F. Miller, 1961], it became obvious that Century. the central place in formation and maintenance of full functioning of system of an immunogenesis of an organism belongs. Final opinion on Century. as the central body of immunity it was created after identification and detailed studying of inborn immunodeficient diseases at the person and animals called by an aplasia or a hypoplasia of Century.

Century. for the first time appears at vertebrata. At the highest fishes it is already eumorphic. It is more studied Century. at birds and mammals. At birds of Century. consists of the ovoid beads located on both sides of a neck which removal leads to disturbance of cellular reactions of immunity. At the majority of mammal Century. it is presented by 2 — 3 shares and located in retrosternal area.

Embryology

Fig. 1. Embryonal laying of a thymus at the person (scheme): and — derivatives of visceral furrows on 16 — the 18th day of uterine life; — derivatives of visceral furrows by the end of the second month of uterine life (the I—V — visceral furrows). 1 — a rudiment of a thyroid gland; 2 — a shchito-lingual channel; 3 — a rudiment of parathyroids (front couple); 4 — a rudiment of parathyroids (back couple); 5 — rudiments of a thymus (are designated in gray color); 6 — ultimobranchial little bodies (derivative the V visceral furrow); 7 — an acoustical (eustachian) pipe and a tympanic cavity; 8 — a rudiment of an almond (points designated the lymphocytes which accumulated around it); 9 — the parathyroids which are standing apart from III and IV visceral furrows; 10 — a timo-pharyngeal channel; 11 — an aortic arch; 12 — the right general carotid artery; 13 — the right subclavial artery; 14 — the left subclavial artery; 15 — shares of a thymus.

Century. belongs to group of the branchyogenic bodies developing from visceral furrows (fig. 1). At the person of Century. there are on the 6th week of pre-natal development in the form of pair protrusion III and IV couples of visceral furrows, but rudiments from the IV couple remain small and can be reduced. It is possible that in formation of rudiments of Century. also the ectoderm of a bottom of branchiate furrows takes part. Epithelial rudiments of gland grow in the caudal direction. A distal part them is thickened, forming a body of gland, and a proximal part is extended in ductus thymopharyngeus which disappears further, and gland stands apart from the visceral furrow which gave it rise. With the continuing growth in length towards heart distal parts of bookmarks approach and closely adjoin to each other, however their real merge does not happen, and the described body has a two-share structure. To the middle of the 8th week of pre-natal development of embedding. go down under a breast to the area of a mediastinum where lie on a front surface of a pericardium. Cervical part of bookmarks remains narrow and is gradually reduced. At a persistirovaniye cranial additional cervical Century can arise tyazhy.

At early stages of an embryogenesis embedding. a little in what differs from laying of other glands and has an appearance massive epithelial tyazhy. Within the 2nd month of development compact epithelial tyazh form outgrowths in a surrounding mesenchyma rich with vessels, and the rudiment of gland becomes lobular. From the beginning of differentiation of fabric of a rudiment, approximately from the 10th week of development, the epithelium of bookmarks gradually acquires loose reticular structure. In loops of a reticulum roundish large basphilic lymphoid cells which, breeding, give rise to numerous small lymphocytes (thymocytes) are located. The quantity them quickly increases, especially at the beginning of the 3rd month of development of a germ. Density of an epithelial reticulum becomes unequal in the central and peripheral sites of gland, and peripheral departments infiltrirutsya plentifully by lymphocytes. At 10 — 11 - week go an embryo in embedding. it is already possible to distinguish brain and cortical substance. To the 12th week of embryonic development in marrow the first little bodies of Century appear. (Gassal's little bodies), the growing mesenchymal fabric finally divides the epithelial remains. After the 18th week of embryonic development of Century. looks quite created lobular body with clear split into cortical and brain layers, reminding rather lymphoid body, than the developing gland.

In the course of an embryogenesis of Century. finally forms before other adenoid tissues (a spleen, limf, nodes) and by the birth it appears the biggest lymphoid body organ.

The epithelial origin of a reticular basis of gland does not raise doubts. The origin of lymphocytes remains not clear. The question of mesenchymal genesis of lymphocytic cells (A. A. Maximov, 1909) which was considered solved is reconsidered again after pilot studies of Auerbach (R. Auerbach, 1961 — 1963) who allows possibility of lymphocytes from epithelial embedding. A necessary condition for this transformation, in his opinion, is the inducing influence of a surrounding mesenchyma.

Anatomy

Century. consists of two the unequal size of shares — right and left, soldered by friable connecting fabric. Sometimes between the main shares intermediate puts. On a configuration of Century. reminds the pyramid turned by top up. Parenchyma of its soft consistence, pink-gray color. Distinguish a body and four horns of Century.: two upper (cervical) the acute, reaching sometimes a thyroid gland, and two lower (chest) rounded off, wide, forming the basis Century. More rare Century. can consist of one or three shares and it is very rare from bigger number of shares (to 6). A cervical part, narrower, is located along a trachea behind m. sternohyoideus and m. sternothyreoideus and sometimes reaches a thyroid gland. A chest part, extending from top to bottom, goes down behind a breast to the III—IV level of a mezhreberye, covering big vessels of heart and an upper part of a pericardium. Sizes and weight of Century. change (age involution) with age.

The relation of weight of gland to body weight (at newborns 1: 300) shows that from the moment of the birth the continuous decrease in its relative weight continuing approximately to 30-year age begins. In process of reduction of Century. its parenchyma is gradually replaced with fatty tissue. At advanced age on site of gland the so-called adipose body is found, segments to-rogo are presented by fatty tissue. However in these segments till an extreme old age the remains of a parenchyma of Century remain.

Blood supply of Century. it is carried out from aa. thoracicae int., rr. mediastinales and dd. pericardiacophrenicae. The arteries departing from these trunks (aa. thymicae) enter gland, branch on interlobular layers and, getting in segments, give capillaries preferential to a bast layer. Marrow is poor in capillaries. Veins (vv. thymicae) go parallel to arteries and fall into vv. brachiocephalicae and in vv. thoracicae int.

B. has well developed intraorganic limf, the system presented by deep and superficial network of capillaries. In brain and cortical substance of segments the deep capillary network is located, and capillaries around Gassal's little bodies are found (a little body of a thymus — corpusculum thymi, LHN). In the capsule of gland and directly under it there is a superficial network of capillaries connected to capillaries of a bast layer. Limf, is more than capillaries in cortical substance (E. A. Vorobyova, 1961). Limf, capillaries gather in the vessels of interlobular partitions going along blood vessels. Limf, vessels of Century. nodes of a front mediastinum and tracheobronchial nodes fall in limf.

The innervation of gland is carried out by branches of a vagus nerve, and also the branches of a sympathetic nerve originating from lower cervical and upper chest nodes (a star-shaped node) of a sympathetic trunk.

Histology

Fig. 2. Structure of a segment of a thymus: 1 — cortical substance; 2 — a small fatty segment in the capsule of gland; 3 — marrow; 4 — an interlobular connective tissue layer; 5 — a little body of a thymus (Gassal's little body); 6 — a blood vessel in an interlobular layer.

Century. it is covered with the connective tissue capsule, from a cut glands dividing a parenchyma on segments of the different size depart a partition (septum). The capsule and a septum contain collagenic and reticular fibers. On the course of blood vessels of small caliber in a parenchyma of Century. the dense network of reticular fibers is found. In each segment irrespective of its size also marrow (fig. 2) differs cortical. The basis of a segment is made by friable, gubkopodobny network of star-shaped epithelial cells, loops cover infiltrirovana with lymphocytes of Century., similar on structure on small lymphocytes and the representing cells to dia. apprx. 6 microns with a dense kernel round optically and narrow basphilic cytoplasm. In a light microscope they are not otlichima from lymphocytes of other lymphoid bodies, but at a submicroscopy distinctions in volume of cytoplasm, quantity of organellas, content of nucleic acids, an alkaline phosphatase are revealed. However these distinctions are not essential and do not allow to differentiate lymphocytes of Century. and lymphocytes of other lymphoid bodies. In subcapsular area of cortical substance the layers of cells similar to lymphoblasts and characterized by high mitotic activity are visible. Besides, in the field there are microphages with granules at cytoplasm which give positive CHIC reaction. Accumulation of lymphocytes between star-shaped epithelial thymocytes (epithelial cells of Century.) gives to cortical substance a characteristic look and dark coloring in drugs.

Marrow has lighter coloring in connection with rather small amount of lymphocytes and dominance of a setevidny epithelial basis. Characteristic educations for a medulla are Gus's little bodies of la representing concentric accumulations of the regenerating star-shaped epithelial cells. In a cortical layer of a little body of Gassal are absent. Besides, at a medulla there are large epithelial cells with a round pale kernel and slaboatsidofilny cytoplasm, in a cut by means of a submicroscopy the dense granules and vacuoles filled with amorphous substance are revealed. The histochemical analysis shows presence of acid and neutral mucopolysaccharides at a detritis of many little bodies of Gassal. Granules of star-shaped epithelial thymocytes and Gassal's little bodies positively react to glycoproteins that demonstrates vigorous secretory activity of epithelial formations of a medulla of Century. It is noticed that formation of little bodies of Gassal results from accumulation of the flattened epithelial cells around the cell containing sekretopodobny substance.

Fig. 3. Site of a thymus of a fruit 21 cm long. The arrow specified the conjunction by means of a desmosome of two epithelial cells (the diffraction pattern; X 18 000).

In cortical and marrow there are macrophages and in a small amount eosinophilic and neutrophilic leukocytes, mast cells. At children of early age in Century. sometimes ochazhka of an erythrogenesis are found. By means of a submicroscopy it is established that the epithelial reticulum is formed thanks to the fact that the stretching epithelial thymocytes remain the shoots connected among themselves. Shoots densely adjoin with each other and connect by means of desmosomes (fig. 3).

Under the capsule on the course of interlobular partitions and around vessels the epithelium forms the continuous layer with a basal membrane which is completely separating lymphocytes of Century. from other fabrics. The gemato-timichesky barrier which consists of cells of an endothelium, an endothelial basal membrane, fine-fibered fabric, a basal membrane of an epithelium and a layer of star-shaped epithelial thymocytes is revealed [D. Pinkel, 1968]. In many epithelial cells fagirovanny material, including lymphocytes is found. They keep desmo-somalny communication with an epithelial basis of a segment.

In a normality in Century. there are no germinal centers characteristic for limf, nodes and a spleen. Proliferation of lymphocytes of Century. occurs out of communication with certain reactive centers. Cells of Century., hl. obr. cortical substance, differ in high mitotic activity, much higher, than in other body tissues. Mitoses in a thymus are observed more often than in adenoid tissues. The DNA updating in Century. occurs more intensively, than in other fabrics.

Age features of a thymus

With age in Century. there are involutional processes which are expressed in change of cellular structure of body.

Weight of Century. considerably varies as individually, and during various age periods.

According to various authors, at newborn children of Century. from 7,7 to 34,0 g weigh. Reliable increase in weight of Century. is registered aged from 1 up to 3 years. During the period from 3 to 20 years note stabilization of weight of Century. At people of advanced age and at old men of Century. about 15 g weigh on average.

With age the ratio between cortical and marrow of Century changes. At fruits by the birth of Century. it is characterized by dominance of cortical substance over brain, abundance of the capillaries penetrating segments; each segment contains 4 — 8 little bodies of Gassal. Has similar structure Century. the child till 1 year. By this time Gassal's little bodies increase at the rate to 80 — 100 microns. Century. the child of 1 — 3 years it is presented equal by the size brain and cortical by layers, at this age the number of capillaries decreases and the number of large-caliber vessels increases. At the same time process of involution of Century begins. KZ in a segment reveal to years up to 3 — 4 little bodies of 130 in size of Gassal — 170 microns. Further narrowing of cortical substance happens to isolation of the follikulopodobny centers at the age of 4 — 9 years, proceeding and in the subsequent up to 20 years due to decrease in number of lymphocytes of Century., further isolation of the follikulopodobny centers consisting of lymphocytes, Gassal's little bodies (1 — 4 on a segment) which reach the maximum size (300 — 400 microns). In 21 — 30 years the number of lymphocytes of Century falls. At people at senile age cortical substance and the remains of Century almost completely disappears. are presented by epithelial components at which there are rare little bodies up to 20 — 50 microns of Gassal. The vascular network is presented by large-caliber arteries and veins. The fatty tissue in interlobular space is considerably developed. However Century. completely does not atrophy, and its sites surrounded with fatty and connecting tissue remain till an extreme old age.

In development functional activity of cells of Century changes. in implementation of immunological reactions. So, it is established that lymphocytes of Century. in vitro begin to react to phytohemagglutinin (FGA) and in the mixed culture of lymphocytes from the 12th week of pre-natal development of the person. Maximum lymphocyte activity of Century. it is noted on 14 — 18th week with the subsequent decrease to the 20th week. Histocompatibility antigens are found on lymphocytes of Century., since the 12th week the Vnutritimichesky phagocytosis of lymphocytes similar to the process which is taking place in Century. the adult, it is found in 15 weeks fruits. The given facts of development of a functional lymphocyte activity

of Century. matter for use of Century. a fruit as a transplant to patients with immunological insufficiency. In literature cases of development of reaction «a transplant against the owner» at children are described, the Crimea transplanted an embryonal thymus gland for the purpose of treatment of a congenital immunodeficiency disorder.

In the course of involution of Century. decrease of the activity of cells of a bast layer whereas cells of a medulla in an active state come to light in Century takes place. old people among cells of fatty and connecting tissue.

According to the selection and clonal theory of immunity F. Burnett lymphocytes of Century. are immunocompetent cells. In the embryonal period in Century. in the presence of antigens of own fabrics there is a suppression of clones of the cells competent to these fabrics, i.e. the «prohibited» clones. It is supposed that lymphocytes of Century., the lives moved in the first days from a thymus gland, give rise to populations of lymphocytes in peripheral lymphoid bodies, keeping the properties received in a thymus gland. F. Burnett believes that the similar mechanism of suppression of the «prohibited» clones is available also for adults, but is expressed in much smaller degree. An animal (e.g., to mice) with removed at the birth of Century. it is possible to recover an immune responsiveness if to enter them within the first week of life lymphocytes of Century., spleens and limf, nodes from immunological mature donors of the same line. Change animal, timektomirovanny at the birth, and also a mature animal after radiation immunological of competent cells from the donor of other line causes in the recipient a disease «a transplant against the owner», edges is that the postponed cells develop an immune response against tissues of the owner. The thymectomy after the first week of life causes a lymphopenia, but essential disturbances of reactions of cellular and humoral immunity do not happen. However later a long time (1 — 2 years) at mice who underwent a thymectomy find decrease in a number of immune responses. W. Dameshek considers that a source of a pathological clone of cells, impetuously proliferating at immunoproliferative frustration (a lymphoid leukosis, a lymphosarcomatosis, a reticulum cell sarcomatosis, a myelosarcomatosis, etc.), are as well as at other autoimmune diseases, the «prohibited» clones. The given hypothesis, though does not cover a pathogeny of all forms of leukemia, but nevertheless is of considerable interest.

Coincidence of the periods of increase in activity of a thymus gland (to 5 years and the pubertal period) with two waves of increase in frequency, on the one hand, of autoimmune, allergic diseases and with another — leukoses is established.

Function of a thymus

Functional activity of Century. in an organism it is mediated, at least, through two groups of factors: cellular (products of T lymphocytes) and humoral (secretion of a humoral factor).

Participation of Century. in development and functioning of immune system it is convincingly proved in experiments on timektomirovanny animals, overseeing by bestimusny animals and children. The thymectomy within the first days of life at animal some types (mice, rats, hamsters, etc.) leads to development of «vasting-syndrome» (English wasting exhaustion). Lag in weight, loss of wool, defeat 'skin and intestines, a hemorrhage, atrophic changes in various bodies, development of inflammatory processes takes place. Atrophic changes in lymphoid bodies with deficit of lymphocytes and a lymphopenia are most characteristic, disturbance of immunological reaction is a consequence of what. First of all the T-system of immunity suffers (see. Immunity , Immunity transplant ). At animals with removed Century. rejection of allogenic transplants of skin or vaccinated tumors is not observed, reactions as hypersensitivity of the slowed-down type do not develop; cells of a spleen are not capable to develop reaction «a transplant against the owner», etc. Later also the B-system of immunity suffers, products of antibodies are broken. At the age of 3 — 4 months such animals perish. The mice of «nude» differing in existence of an autosomalny recessive gene «пи» also perish in the same terms; they have signs of a syndrome of exhaustion. Idiosyncrasy of mice, homozygous on a gene «пи», the inborn aplasia of Century is. Vasting-sindrom does not develop after removal of Century. at mature animals, and also after a neonatal thymectomy at rabbits, dogs and other animal species at which by the time of the birth other lymphoid bodies are developed. Removal of a spleen or the maximum extirpation limf, do not lead nodes in the neonatal period to development of a syndrome of exhaustion.

Clinical signs of a syndrome of exhaustion with deficit of T-system of immunity are revealed at children with an aplasia or a hypoplasia of Century. After a thymectomy at adults concerning a myasthenia development of strong indications of a syndrome of exhaustion is not revealed. However a condition of immune system at patients after removal of Century. it is a little studied. It is necessary to consider also that the ectopic centers of a timichesky parenchyma connected with thyroid or parathyroids capable to function after removal of ground mass of Century are found in 20% of people. [Havard (Page W. Havard), 1970].

Such observations formed the basis for a conclusion that Century. is the central body of system of an immunogenesis which is put and ripens before other lymphoid educations. Limf, nodes and a spleen are considered as peripheral bodies of immune system. Before maturing of peripheral lymphoid bodies of Century. is a vital; in an adult organism of Century. only fills population of timuszavisimy lymphocytes, but its participation in immune processes is undoubted. It is established that under the influence of Century. the population of T lymphocytes (timuszavisimy, timusproiskhodyashchy) which is carrying out reactions of cellular immunity whereas other population — the B-lymphocytes (timusnezavisimy) occurring perhaps, from the adenoid tissue connected with intestines or marrow participates in reactions of humoral immunity (antibodyformation) forms.

The greatest recognition was gained by the point of view that in Century. there is a process of a differentiation of a polipotentny stem (parent) hemopoietic cell of a marrowy origin through a number of stages in an immunocompetent T lymphocyte. Development of T lymphocytes from a stem hemopoietic cell is authentically tracked by means of radioactive marked cells, and also cells bearing a chromosomal marker. The parent hemopoietic cell on a blood-groove arrives in Century., where under the influence of cellular and humoral influences it is differentiated in a lymphocyte of Century., and then in the T lymphocyte which gains properties of an immunocompetent cell and leaves Century., creating population of lymphocytes in so-called timuszavisimy zones limf, nodes and a spleen.

In Century. allocate four various structural zones in which there is a formation of T lymphocytes: an outside subkapsulyarny cortical layer of cortical substance where proliferate big lymphoid cells and new lymphocytes of Century are formed.; an inner cortical layer in which again arisen thymocytes migrate; actually the medulla and sites of perivascular connecting fabric surrounding large vessels of a medulla [L. Clark, 1973]. The Subkapsulyarny layer of cortical substance is considered the basic, in it there is a proliferation of stem cells to formation of new lymphocytes of Century. It is supposed that stem cells come to a subkapsulyarny layer by means of emigration from the capillaries forming numerous arcades. The majority of cells in this layer is presented by big lymphocytes with extraordinary high proliferative activity (on average 6 — 9 hour/cycle). The following process of a differentiation is made in the inner layer of cortical substance where find slaboproliferiruyushchy small lymphocytes in the basic. It is considered that lymphocytes leave Century. through a medulla on veins and limf, to vessels. Cells perivaskulyarno participate in the same process!! connecting fabric. Transition of lymphocytes of Century. from cortical in marrow is followed by change of some of their properties: timusspetsifichesky antigenicity and sensitivity to a hydrocortisone decreases, the level of antigens of histocompatibility increases and there is an ability to react to FGA and other stimulators. Formed in Century. T lymphocytes come to a lymph and to blood and then colonize timuszavisimy zones in limf, nodes (a paracortical zone) and in a spleen (a zone of lymphocytes around the central arteriole of a lymphoid follicle). Process of colonization is not accidental. As a result of a differentiation lymphocytes of Century. acquire the superficial structures promoting purposeful colonization of timuszavisimy zones. Most accurately deficit of lymphocytes in timuszavisimy zones comes to light at mice, timektomirovanny in the neonatal period, at mice of «nude», at patients with hypo - and an aplasia of Century. Recovery of population of lymphocytes in these zones is observed at animals and at the person is after implantation of Century.

Products of lymphocytes in Century. is rather stable process subject to influence of age and genetic factors. High activity of a timichesky lymphocytopoiesis is noted at the person at the end of an antenatal life and in the first years after the birth, i.e. during the periods of formation of system of an immunogenesis. Then Century. the hl is exposed to physiological involution with decrease in limfotsitopoetichesky activity. obr. in a bast layer. On products of lymphocytes of Century. various influences exert impact. So, at various stressorny influences (starvation, overheating or overcooling, a severe injury, the exhausting physical activity, serious inflammatory or infectious diseases etc.) involution of Century is noted., followed by mass death of T lymphocytes, but if a stress not long, then Century. quickly regenerates. The close interrelation between activity of bark of adrenal glands and products of lymphocytes of Century is established. The significant role in restriction of products of T-cells is played by adrenal hormones. So, it is noted that at mice in 2 — 3 days after introduction of a hydrocortisone in Century. there are only 5 — 10% of the lymphocytes presented by T-cells. On the other hand, established facts of the regulating influence of Century. on a differentiation of closed glands, and in particular bark of adrenal glands, in early ontogenesis [Pirpaoli, Sorkin (W. Pierpaoli, E. Sorkin)].

The Timuszavisimy lymphocytes making the greatest part of recirculating small lymphocytes of blood and a lymph perform important immunological functions. These cells are capable to distinguish the antigen coming to an organism and depending on features of the last through a number of stages of proliferation and a differentiation to turn into the cells effectors providing an effector phase of an immune response. The similar effector mechanism develops at reaction of an organism as cellular immunity (e.g., rejection of an alien transplant, a tumor, at protection against a number of bacterial and viral infections). Cells effectors at interaction with specific antigenic material allocate a number of nonspecific factors — the mediators of cellular immunity (a factor, oppressing migration of macrophages, a blastogenic factor, etc.) participating in the final stage of an immune response. Other functional feature of timuszavisimy lymphocytes is their ability to interact with B-lymphocytes after activation by antigen (so-called timuszavisimy antigens) and to direct a way of a differentiation of the last to the plasmocytes producing antibodies. Since the end of the 60th years intensively study the suppressive function of T lymphocytes consisting in regulation of products of antibodies. Assume that switching off of this function of T lymphocytes can serve as the reason of development of autoimmune processes. Besides, the important part in elimination from an organism of the mutated cells, i.e. participation in maintenance of a genetic homeostasis is assigned to T lymphocytes. Therefore, Century. represents the body producing the immunocompetent T lymphocytes which are carrying out the vital immunological functions in an organism.

In addition to products of T lymphocytes of Century., it is established that this body cosecretes a humoral factor. Metcalf (D. Metcalf, 1956) showed that blood serum of the mice and people having leukemia stimulates a lymphopoiesis at newborn mice. Such factor was called limfotsitopoezstimuliruyushchy and in insignificant quantities is revealed in blood serum of healthy mice and people. In experiments influence of this factor on function of T lymphocytes is proved: recovery of immune responses in the neonatal period at timektomirovanny mice was noted (cells limf, nodes or a spleen have no similar ability); extracts of Century. promote development of immune processes in timektomirovanny animals; after an incubation with extract of Century. cells of a spleen of the mice deprived of a thymus gland soon after the birth gain ability to develop reaction «a transplant against the owner», like cells of normal animals. The Timichesky factor which is present in blood, and also extracts of Century. exert impact on the level of the rosette-forming cells formed by T lymphocytes. Miller (J. F. Miller, 1974) gives results of effect of extract from Century., called «timopoetiny», on induction of unripe pretimichesky cells in T lymphocytes.

The incubation of hemopoietic cells of in vitro with timopoetiny during the short term (2 hours) led to emergence of cells with the surface antigens characteristic of the differentiated T lymphocytes. Drug induced only a differentiation of cells with timusspetsifichesky antigens. Because acquisition of timusspetsifichesky antigens happens during the short period of an incubation, the conclusion was made that this process does not require cell fission, and emergence of «new» antigens is connected or with their synthesis, or with a demaskirovka on a cellular surface. It is possible to take for granted that the soluble factor produced Century., influences functional activity of timuszavisimy lymphocytes, promoting a differentiation of progenitors in immunocompetent T lymphocytes. There are data that this factor activates enzymes of cellular membranes (activation of adenyl cyclase is noted) and increases the cellular level of the cyclic adenosinemonophosphate necessary for induction of immunocompetence [Cook, Treynin (A. Kook, N. Trainin, 1963)].

However many questions connected with secretion of this timichesky factor remain not clear. In various laboratories drug of different chemical structure (a protein, peptide, etc.), a pier is received. weight (from 400 to 200 000) and with different properties [Lakki (T. D. Luckey), 1973]. It is supposed that the humoral factor cosecretes the star-shaped epithelial thymocytes located in all departments of Century., in which find an acid glycoprotein. It is not excluded that processes of a differentiation (a stem cell — a thymocyte — the T lymphocyte) appear under the influence of the humoral factors produced by epithelial elements of Century. There is also an opinion that allocation of a soluble humoral factor of Century. can happen to participation of little bodies of Gassal [P. Kater].

Also participation of Century is shown. in regulation of a number of the vital functions. So, e.g., hormone of Century. takes part in control of neuro and muscular transfer, a condition of carbohydrate metabolism, exchange of calcium. Century. closely interacts with hemadens (a hypophysis, adrenal glands, a thyroid gland, gonads, etc.) - In experiments with removal of various closed glands at kept Century. and with removal of Century. in the presence of endocrine organs distinction of level of the interaction influencing products of lymphocytes was shown [I. Comsa, 1973]. Antagonism between timichesky hormone and thyroxine, glucocorticoids and hormones of Century is shown., synergism of effect of hormone of Century. with a growth hormone of a hypophysis. Komza provides proofs that in operation on products of lymphocytes timichesky hormone is an antagonist of corticotropic influence of a front share of a hypophysis and, apparently, inhibits limfolitichesky effect of corticotropin, a cut is mediated by bark of adrenal glands.

Thus, it is already possible to generalize the main functional features of this body. Function of Century. it is impossible to consider separately from a state immunity (see), in particular T-systems. A thymus gland the occurring lymphocytes in the form of the aptigenraspoznayushchy cells, cells effectors, cells assistants or cells regulating products of antibodies antibody producers participate in the majority of immune responses of an organism.

On the basis of the leading role of timuszavisimy lymphocytes in F. Vernet's immunity formulated the concept about immunological surveillance, allocating as the main task of immunity protection of genetic constancy of internal environment of an organism. As an effect of disturbance of immunological surveillance infectious diseases, autoimmune frustration, the increased probability of developing of tumoral diseases can serve in an organism. In this regard idea of atrepsy gains new development. The generalized data confirm increase in frequency of tumoral diseases at children with immunological insufficiency (hl. obr. at defeat of timuszavisimy system), at recipients of gomotransplantat (generally kidneys), it is long receiving immunosuppressive therapy (see. Immunodepressive states ), and also in an experiment at timektomirovanny animals right after the birth [Gatti, Goode (R. Gatti, G. A. Good)].

Decrease in functional activity of Century., decrease of the activity of T lymphocytes in reactions of cellular immunity, increase in frequency of autoimmune diseases and new growths formed the basis for promotion of the immunological theory of aging [R. L. Walford].

According to S. S. Vasileysky, Yu. M. Lopukhin, R. V. Petrov (1972) data, Century., except well-known induction function concerning system of an immunogenesis, possesses the braking action in relation to a nek-eye to the systems characteristic of the embryonal period. Synthesis of embryonal proteins, derepressirovanny in situations with switched off Century can be an example of the last. (e.g., at patients with an ataxy teleangiectasia), such as alpha-fetoprotein, beta fetoprotein, emergence of monomeric subunit of IgM5 of the immunoglobulin M presented at the adult by the whole pentomer.

Pathological anatomy

Circulatory disturbances in the form of a venous plethora of Century. often occur at mortinatus and newborn at asphyxia, at children of chest and early age at acute, preferential respiratory, viral infections, sepsis, toxic dysentery, diphtheria. Parenchyma of Century. it is edematous, cyanotic, with dot petekhialny hemorrhages. The considerable plethora and hypostasis with increase in volume and weight of body can simulate a hyperplasia of Century. In rare instances at newborns and babies massive hemorrhages in Century are observed.

Inborn (primary) aplasia and a hypoplasia are characterized by total absence of a parenchyma of Century. or its extremely poor development. Similar changes find at children of younger age at a number of the inborn hereditary diseases united in group of immunodeficient — «the Swiss syndrome», Di George's syndrome, an ataxy teleangiectasia (Louis Bar syndrome), etc. (see below Diseases of Century.).

Fig. 7. Lack of little bodies of Gassal in a segment of a thymus at its inborn hypoplasia.

Considerable defeat of system of T lymphocytes is characteristic of these diseases. In cases of an aplasia a parenchyma of Century. it is not found. At a hypoplasia of Century. it is reduced, cortical and marrow timichesky little bodies of Century are indiscernible because of trace amount or total absence of lymphocytes. are absent or meet in the form of single structures of an atypical look. At extreme degrees of a hypoplasia of a segment of gland are presented only by cells and fibers of a stroma (tsvetn. fig. 7). In peripheral blood of such children the number of lymphocytes is sharply lowered, reactions of cellular immunity are oppressed (the slowed-down rejection of an alien transplant, decrease in reaction of hypersensitivity of the slowed-down type and contact skin sensitivity, the blastogenic response of lymphocytes of blood on FGA and allogenic lymphocytes, etc. is lowered). At the most serious illness — «the Swiss syndrome» — children usually perish aged till 1 year with signs of a syndrome of exhaustion.

Atrophy of a thymus (secondary, passing or so-called aktsidentalny involution of Century.) at children develops at a number of the diseases proceeding with the phenomena of intoxication (e.g., a severe form of pneumonia, long pyoinflammatory processes, etc.), at stressful reactions, long corticosteroid therapy, beam influence, etc. At aktsidentalny involution quickly there is a decrease of lymphocytes of Century. with falling of weight and volume of body.

Fig. 6. Increase in quantity of little bodies of Gassal (red color); expansion brain and narrowing cortical layers at aktsidentalny (accidental) involution of a thymus.

In the first phase of aktsidentalny involution lymphocytes break up and are partially englobed by macrophages of Century., retikuloepiteliya it giperplazirutsya, the plentiful quantity of little bodies of Gassal is formed, cortical substance from a decrease of lymphocytes becomes lighter brain (inversion of layers), the weight of gland falls, its segments are fallen down (tsvetn. fig. 6). Further the atrophy of an epithelium is observed, the quantity of little bodies of Gassal decreases, their contents are hyalinized, obyzvestvlyatsya, segments are sharply fallen down, interlobular connecting fabric fibrozirutsya. Degree of an atrophy is proportional to duration and disease severity. On early phases process of aktsidentalny involution is reversible, at the same time structure of segments of Century. (cortical and marrow) it is completely recovered. In a phase of a considerable atrophy process is irreversible. Far come atrophy of Century. usually it is found on section at it is long also hard being ill children. Studying of a structure of Century. at various pathology of newborns with a parallel research 7 of globulins of serum did not reveal natural changes.

True hypoplasia of Century. it is necessary to distinguish from acquired. At a true hypoplasia and an aplasia of Century. it is about total absence or an underdevelopment of an epithelial reticulum and lymphocytes of a thymus gland, at the same time Gassal's little bodies or completely are absent, or the quantity them is sharply reduced and they are small. About a hypoplasia it is difficult to judge only by quantity of lymphocytes since their quantity sharply falls also at aktsidentalny involution.

The hyperplasia of a thymus is followed by increase in number of cells in cortical and marrow or disturbance of a structure of Century. in connection with emergence of additional educations (e.g., the germinal centers). According to Birikh (Y. Bierich), the true hyperplasia is observed at 1/3 well somatic of the developed children of the first year of life since during this period of life of Century. it is most functionally loaded. Hyperplasia of Century. it can be connected with change of usual structure that is observed at a number of the diseases proceeding as autoimmune (a malignant myasthenia, a system lupus erythematosus, etc.)*. So, at a malignant myasthenia in 70 — 80% of cases increase in a medulla at the expense of an atrophy cortical, emergence of the germinal centers characteristic for limf, nodes, accumulation of plasmocytes around vessels is found. Despite emergence of additional structures, the size of Century. can not increase.

Fig. 5. The huge thymus which caused sudden death in the boy of 2,5 months. In the capsule dot hemorrhages.

It is necessary to distinguish a timomegaliya from a true hyperplasia (tsvetn. fig. 5) at so-called. status thymicolymphaticus (see). The etiology of an inborn timomegaliya is not clear. Timomegaliya is observed at some endocrine diseases (thyrotoxicoses, an acromegalia), in certain cases bronchial asthma at children. Century. at a timomegaliya it is rich with lymphocytes, a bast layer its wide, the sizes and quantity of little bodies of Gassal are reduced, the medulla is narrowed. At a timomegaliya of Century. does not give reactive aktsidentalny involution since function of regulation of proliferation and disintegration of lymphocytes of Century is broken., edges normal it is carried out by a timichesky epithelium and Gassal's little bodies [Blau, Hirokava (J. N. Blau, To. Hirokawa)]. The persons suffering from a timomegaliya quite often perish in the most unexpected situations (e.g., an anesthesia, bathing, etc.). On autopsy find increased in a size and in the weight of Century., increase limf, nodes and hypoplasia of adrenal glands. It is supposed that the lethal outcome is connected not so much with a timomegaliya of Century., how many with hypofunction of bark of adrenal glands.

The inflammation of a thymus (thymitis) usually develops as a complication at pyoinflammatory diseases of fabrics of a front mediastinum. Hron, a thymitis can proceed as sclerosing process.

Fig. 4. Formation of the large merging Gassal's little bodies (it is specified by shooters) in a thymus at an acute leukosis.

At various malignant tumors both at children, and at adults in Century., except sharp falling of its weight at the expense of a decrease of lymphocytes and a collapse of segments, considerable activation of epithelial thymocytes with formation of very large merging Gassal's (fig. 4) little bodies and existence of plasmocytes is noted. Value of these changes remains not clear.

At lymphoid forms of an acute leukosis at children leukemic infiltrate rather often originally arises in Century., elements a cut at the same time are completely forced out by leukemic infiltrate. At myeloid, gistiomonotsitarny and other forms of leukoses in Century. aktsidentalny involution is observed.

Methods of a research

Researches of Century. shall be directed as to assessment of a somatic condition of gland, and to assessment of timuszavisimy lymphocytes.

Structural changes in Century. can be revealed at a research of the material received at its biopsy.

X-ray inspection of a thymus. Apply a number of ways of size discrimination of Century. by means of radiological methods: typical shadow of Century. it is possible to receive on the x-ray films made in direct, side or slanting projections; tomography (see) allows to receive a series of pictures, eliminating effect of summation of shadows; pnevmomediastinografiya (see) with contrasting of bodies of a mediastinum gas (the slanting projection is more preferable) provides optimal conditions for identification of Century.

Normal Century. usually does not give the isolated image on roentgenograms and tomograms and it can be revealed only at a pnevmomediastinografiya.

Fig. 5. The hypertrophy of a thymus which is moderately expressed (it is specified by an arrow). Roentgenogram.
Fig. 6. A huge hypertrophy of a thymus (it is specified by an arrow). Roentgenogram.

At inborn and acquired (shift of gland at pathological processes in bodies of a mediastinum) allotopias and at a hypertrophy of iron are occupied by a regional arrangement on the right or left side of a mediastinum in the form of a ledge with the rounded outlines (fig. 5); at a hypertrophy there can be also bilateral vystupaniye of gland. In a side projection the shadow of gland appears in an upper part of a front mediastinum. The allotopia and a hypertrophy should be differentiated with paramediastinal educations (paramediastinal pleurisy, an atelectasis of an apical segment of a lung, paratracheal giperplazirovanny limf. nodes). In addition to polyprojective researches of a thorax, apply a tomography and a pnevmomediastinografiya to distinguishing. At a huge hypertrophy (fig. 6) a shadow of Century. can occupy a considerable part of the pulmonary field. It is necessary to differentiate with cysts and tumors of lungs and mediastinums for what resort to a tomography, a pnevmomediastinografiya and in rare instances — to artificial pheumothorax. The most important radiological symptoms of thymomas: a form of «pancake», a bilateral vystupaniye with hilly polycyclic outlines and long arches (at other mediastinal tumors of an arch shorter); infiltrative growth of a tumor up and from top to bottom with penetration into the next bodies. Various types of thymomas — cancer, sarcomas (lymphosarcoma), a lymphoepithelioma — usually do not manage to be distinguished only according to radiological data.

There is also a so-called timolitichesky test when a repeated radiographic research increased Century. the child will be seen off after administration of corticosteroid hormones: the sizes of a thymoma after test remain not changed.

Functional assessment of T lymphocytes. A number of in the vitro and in vivo methods is developed for the analysis of function of timuszavisimy lymphocytes. For assessment of T lymphocytes of in vitro the following tests are recommended. 1. Reaction of a blastotransformation of peripheral blood lymphocytes under the influence of FGA or in the mixed culture of lymphocytes. The lymphocytes allocated from peripheral blood cultivate during 3 days with FGA or during — 7 days with allogenic lymphocytes and in number of blast forms or on inclusion of a radioactive label judge activity of timuszavisimy lymphocytes. 2. Rosetting by lymphocytes. T lymphocytes of the person have ability to interact in vitro with erythrocytes of a ram and to form the figures which received the name of sockets. Identification of spontaneous rosette-forming cells is used as the test for definition of absolute and relative number of T lymphocytes in peripheral blood. At the healthy adult apprx. 60 — 70% of the circulating lymphocytes form sockets with erythrocytes of a ram. Peripheral blood lymphocytes incubate with erythrocytes of a ram of on the fixed drugs count number of the lymphocytes which connected 4 and more erythrocytes of a ram. 3. Products lymphocytes of the factor oppressing migration of macrophages. Lymphocytes of patients, sensibilized nek-ry antigens (e.g., TB patients), at contact with such antigen produce a soluble factor which can be revealed by the test of oppression of migration of macrophages. For assessment of function of timuszavisimy lymphocytes of in vivo such tests as development of skin reactions of hypersensitivity of the slowed-down type for eurysynusic antigens are recommended (tuberculine, trikhofiton, kandidin, Streptokinasa streptodornase, etc.); the answer as the slowed-down hypersensitivity at contact test with 2,4 dinitrobenzene chloride; ability to tear away allogenic transplants. An indirect idea of a condition of timuszavisimy system is given by absolute quantity of lymphocytes in peripheral blood. The listed above tests have the greatest diagnostic value at the diseases connected with switching off of Century. (e.g., immunodeficient diseases with an aplasia or a hypoplasia of Century.).

Diseases of a thymus

Due to the establishment of a role of system of Century. in implementation of immunological reactions in an organism purposeful identification of clinical forms of defeat of Century is conducted. In spite of the fact that many diseases at which in a varying degree suffers Century are revealed., there is no accurate classification of diseases of Century still. It is obviously possible to allocate, at least, 3 groups of the diseases which are characterized by defeat of system of Century.: 1) diseases with an aplasia or a hypoplasia of Century.; 2) diseases with a dysplasia of Century.; 3) tumors of Century.

Diseases with an inborn aplasia or a hypoplasia of a thymus

Inborn, or primary, an aplasia and a hypoplasia of Century. it is characterized by total absence of a timichesky parenchyma or its extremely poor development. Similar changes find at children at a number of the inborn diseases united in group immunodeficient (see. Immunological insufficiency ).

The most expressed defects of development of Century. are found at the following syndromes. 1. Aplasia of Century. and parathyroids or Di George's syndrome — defect of development of the bodies coming from the III—IV couples of visceral furrows. Characteristic symptoms of a disease are spasms, since the neonatal period, and oppression of the reactions mediated by timuszavisimy lymphocytes; on antigenic irritations finds ability to react only an adenoid tissue of V-system. 2. Autosomalny recessive aplasia of Century. with a lymphopenia, or Nezelof's syndrome. The bodies arising from the III—IV visceral furrows develop normally, but almost completely is absent Century. Also falloff of reactivity of T lymphocytes comes to light. 3. The Autosomalny recessive heavy combined immunological insufficiency («the Swiss syndrome»), Limfopenichesky agammaglobulinemia, aplasia or hypoplasia of Century. are combined with a hypoplasia of all adenoid tissue. At such children of Century. it is difficult to identify, and in certain cases find thin epithelial tyazh, deprived of thymocytes and Gassal's little bodies. Along with sharp oppression of reactions of cellular immunity deficit of humoral immunity comes to light. Children usually perish in the first half a year of life.

4. Immunological insufficiency with an ataxy teleangiectasia, or Louis Bar syndrome. Hereditary disease of autosomalno-recessive type. It is characterized by the progressing cerebellar ataxy, teleangiectasias and a dysgammaglobulinemia (see. Ataxy ). Century. is absent or a gipoplazirovana (after the birth of Century. embryonal type). Along with switching off of reactions of cellular immunity patients have the selection deficit of IgA. High frequency of new growths is characteristic of this disease (more often lymphosarcomas, a lymphogranulomatosis, etc.).

All diseases with an aplasia or a hypoplasia of Century. are followed by recurrent inflammatory diseases of sinuso-pulmonic and intestinal localization which quite often are a proximate cause of death of patients. Especially hard inflammatory and infectious diseases at children with «the Swiss syndrome» proceed.

The children, especially early age having recurrent inflammatory diseases shall be carefully inspected on a functional condition of timuszavisimy system of immunity. To lay down. actions at the listed syndromes come down to transplantation of Century. separately or with marrow («the Swiss syndrome», Louis Bar syndrome, Nezelof's syndrome), to introduction of the transfer factor extracted from lymphocytes of sensibilized donors and capable to transfer cellular immunity, and also to symptomatic therapy.

Diseases

In this group are combined with a dysplasia of a thymus diseases of hl. obr. autoimmune: malignant myasthenia (see), system lupus erythematosus (see), autoimmune hemolitic anemia (see), pseudorheumatism (see), Hashimoto's disease (see. Hashimoto disease ), etc. In a thymus gland develop uncharacteristic for normal Century. structures: infiltration of a medulla lymphocytes and plasmocytes, emergence of the germinal centers, aggregation of epithelial cells in a medulla, formation of cysts in Gassal's little bodies, increase at a rate of timichesky segments, in certain cases formation of thymomas, etc. In a clinical picture the symptoms characteristic of each autoimmune disease are presented. Value of changes in Century. in a pathogeny of these diseases it is not found out. On Burnett's hypothesis of a role of Century. in development of autoimmune diseases, education in Century is supposed. so-called forbidden clones of the immunocompetent cells reacting against antigenic structures of own organism. Researches on mice of the NZB line at whom autoimmune processes, similar to those which are revealed at the person, napr, at a system lupus erythematosus develop with age formed the basis for such conclusion. At the same time in Century. the germinal centers develop. On the other hand, it is not excluded that in Century. the mechanisms controlling elimination of such clones are broken i.e. a peculiar immunodeficiency takes place, to-rogo the raised products of antibodies against various antigenic structures of an organism are result. Quite often at such diseases as a myasthenia, a system lupus erythematosus, and some other are made thymectomy (see). The received results of operation are contradictory, only at a myasthenia the thymectomy gives up to 70% of permanent treatment (S. A. Gadzhiyev, M. I. Kuzin). In some cases long remissions whereas in other cases the thymectomy does not yield favorable result are received. Apparently, the result of operation is influenced by a stage of a disease, in to-ruyu make a thymectomy. In quality to lay down. actions at a myasthenia sometimes apply radiation therapy on area of Century., efficiency a cut is lower, than at a thymectomy. Often at the listed autoimmune diseases use immunodepressive therapy, however if the possibility of oppression of the cellular mechanisms regulating products of autoantibodies is not excluded, then this way of oppression of immune responses can strike the controlling systems still more.

Tumors of a thymus

Tumours of a thymus - a thymoma — occur at people of all age groups. According to literary data, the frequency of thymomas fluctuates widely. At adults of a thymoma occur among tumors of a mediastinum in 5 — 14% of cases; at children are more rare (in 8% of cases). Most often thymomas occur at patients myasthenia (see) at mature and advanced age; about 2/@ part of them have tumors of Century. (M. I. Kuzin, 1972; B. P. Volkov, 1974).

The majority of thymomas belongs to to lymphoepitheliomas (see). Depending on a ratio of lymphoid and epithelial elements in a tumor distinguish thymomas with equal quantity of lymphoid and epithelial cells, preferential epithelial or lymphoid types, and veretenoobraznokletochny type. In some cases tumor of Century. consists of elements of a thymus gland and the fatty tissue which is a part of segments of gland — a so-called lipotimoma (timolipoma) which is usually proceeding asymptomatically.

Usually thymomas grow from a middle part of shares of Century. and from the lower horns, are often soldered to a pleura, a pericardium, left brachiocephalic (anonymous) and upper hollow veins. At an allotopia of Century. or the site of its fabric they can sometimes be also in other departments of a mediastinum, a root of a lung, on a neck. The sizes of a tumor vary over a wide range, but small prevail. At any histologic type of a structure of a tumor in the thickness of it the centers of a necrosis, hemorrhage quite often meet the subsequent kistoobrazovaniye, fibrosis. Around vessels and connective tissue trabeculas find accumulations of edematous liquid in the form of cuffs from which cysts can also form. In thymomas with equal quantity of epithelial and lymphoid elements epithelial cells form friable network, in cells a cut thymocytes are diffuzno distributed. In tumors of epithelial type large cells with juicy plentiful cytoplasm, ovoidny, poor chromatin a kernel prevail. Cells densely adjoin to each other, form solid tyazh, places develop in sockets. At gistokhy. a research in epithelial cells of thymomas find a glycogen, granules of glycoproteins and glycolipids that allows to assume existence at them hormonal function and high potential activity. In thymomas with dominance of lymphoid elements the separate epithelial cells or tyazh formed by them, places of accumulation of «foamy» cells of an epithelial origin are visible.

Thymomas have the capsule, have no expansive growth, slowly increase in sizes, as a rule, do not metastasize. In them few figures of a mitosis are also not present an atipizm of cells. It allows to consider them as rather benign tumors. Believe that the metastasizing cells of a tumor are exposed to destruction by antitimichesky antibodies which, as a rule, are found in blood of patients with thymomas. Points existence of plazmotsitarny infiltration of the capsule of a tumor and surrounding fabric of gland, development of the germinal centers to immunological reaction, quite often near the capsule of a tumor.

The malignant thymoma consists of the low-differentiated elements, difficult distinguishable from retikulo-and lymphosarcomas. These tumors of Century. metastasize in the next limf. nodes and remote bodies. Kastlmen (V. of Castleman), J. W. Peabody is considered that the remote metastasises at thymomas are not observed, and existence tells them against a thymoma. At the same time authors specify that malignant thymomas make 32%.

The clinical picture of thymomas is very various. Apprx. 50% of tumors of Century. proceeds asymptomatically and accidentally comes to light during preventive X-ray inspections or it is shown by symptoms of a prelum of bodies of a front mediastinum [Bernatts (Ph. Bernatz), 1961]. At a considerable prelum the feeling of constraint behind a breast, unpleasant feelings and pains, short wind, swelling of cervical veins, puffiness and cyanotic coloring of the person appears. Respiratory disturbances at children owing to a prelum of rather narrow, pliable trachea are especially expressed. Most often thymomas are combined with a myasthenia [on Seybolda (W. Seybold, 1950), Mac-Doneldu (j. McDonald) — 48 — 84%], is more rare with an agammaglobulinemia, aregeneratorny anemia, Itsenko's syndrome — Cushing. In some cases the heavy myasthenia or other syndromes can develop after removal of an asymptomatic thymoma. The syndromes accompanying a thymoma (a myasthenia, an agammaglobulinemia, etc.), force to begin a purposeful research for detection of a thymoma therefore tumors come to light earlier and have rather small sizes. Asymptomatically the developing tumors of Century. reach considerably the big sizes by the time of detection or emergence of symptoms of a prelum of bodies of a mediastinum.

X-ray inspection (a combination of a pnevmomediastinografiya and a tomography) allows to reveal tumors of Century. at 57 — 76% of patients. Tumors of Century. 3 cm in size in dia, and less usually do not come to light at X-ray inspection even on a pnevmomediastinogramma. The shadow of a tumor is better visible in profile and slanting pictures. It is found on average more often or an upper part of a front mediastinum, has the rounded or ovoidny shape. Bystry increase in the sizes of a shadow of a new growth with expansion of a mediastinum in both parties, uneven, undulate, indistinct contours of a big tumor of Century. point out its malignant character. Administration of contrast medium in brachiocephalic veins allows to reveal a prelum or shift of vessels a tumor of Century. Simultaneous defeat of several vessels indicates the malignant growth of a tumor.

The differential diagnosis is carried out with diseases of a thyroid gland (a retrosternal craw), a teratoma, malignant tumors limf, nodes and cellulose of a mediastinum, and also tumors of a breast. In doubtful cases for the purpose of specification of the diagnosis and the choice of a method of treatment make puncture or open (a mediastinoskopiya, a sternal Mediastinotomy) a biopsy with the subsequent histologic research of material.

Treatment high-quality and some malignant (in particular, high-differentiated, usually radiorezistentiy) tumors of Century. preferential surgical. Patients with a syndrome of a myasthenia and other syndromes need thorough preoperative training. Patients with a myasthenia shall be iod observation of both the surgeon, and the neuropathologist. Appoint medicamentous means for the purpose of reduction of weight of dysfunction of skeletal muscles, elimination of disturbances of swallowing, breath, chewing. With the same purpose some authors recommend to carry out preoperative radiation therapy, believing that the operation executed against the background of improvement of the myasthenic status is followed by smaller risk and yields the best results. Operations are performed under an endotracheal anesthesia. Preference is given to those types of anesthesia at which it is possible to count on bystry escaping of an anesthesia without respiratory depression, in particular the combined electroanesthesia (see. Elektronarkoz ). The best access is the median sternotomy with a section of a breast to the V edge or completely (see. Mediastinotomy ). At big tumors and need of expansion of access the section can be prolonged to the right or to the left (after crossing of a breast) on the corresponding mezhreberye (A. Ya. Kabanov). Use of a cross sternotomy and opening of both pleural cavities is unreasonable. It is difficult to remove upper horns of Century from this section., stretching for a neck. Transpleural front and side or side access has no advantages before a full longitudinal sternotomy. Some surgeons apply it when the tumor preferential stands in one of pleural cavities. Great technical difficulties arise at an union of a tumor with brachiocephalic or with an upper vena cava. Careful preparation directly near a wall of a vein in most cases possible to separate a tumor and to remove it. The left brachiocephalic vein can be tied up and crossed.

At germination in an upper vena cava it is necessary to leave a small layer of a tumor over a vessel and to carry out radiation therapy in the postoperative period. Irrespective of radicalism of intervention all patients with a myasthenia are subject to further treatment under observation of the neuropathologist. Along with antikholinesterazny drugs appoint steroid hormones (B. M. Gekht). At malignant tumors of Century., having high radio sensitivity, carry out beam treatment with use of megavoltny sources for the purpose of radical or palliative treatment (for removal of a compression of bodies of a mediastinum) at a total focal dose to 5000 — 6500 I am glad. In some cases radiation can be carried out with front and back water in the ratio doses 2: 1.

Oncotomy of Century. at patients with a myasthenia leads to improvement in 20% of cases, without changes — in 33% of cases. A considerable part of patients perishes in various terms after operation from progressing of a myasthenia, but not from a recurrent tumor. For improvement of results resort to a glomectomy and denervation of a carotid sine, and also to massive therapy by the steroid hormones appointed every other day during a long span.

Operations at diseases of a thymus

the Operative measures connected since Century., can be two types: thymectomy (see) and transplantation of Century.

Transplantation of Century. it began to be applied in connection with identification and studying of diseases with an aplasia and a hypoplasia of a thymus gland. Change of Century. it is recommended at congenital immunodeficiency disorders with defeat of T-system, and also at some diseases with deficit of timuszavisimy system (e.g., a skin and mucous candidiasis). Action transplantirovanny Century. it is connected with products of a humoral factor and T lymphocytes. Cases of development of reaction like «transplant against the owner» at children with the switched-off T-system after transplantation embryonal allogenic are described Century., what testifies to need of selection of the donor and recipient for antigens of system of histocompatability. Source of Century. embryos serve (it is recommended to use Century. after 12 weeks of embryonic development) or the children who died in the antenatal period.

Two ways of transplantation of Century are developed.: in the form of fragments and integral body. Fragments of an embryonal thymus gland size in several millimeters transplant to a thicket to the area of a direct muscle of a stomach. Transplantation of Century. in the form of integral body it is offered by Yu. I. Morozov (1971). As the donor use material from mortinatus children. The breast is excised together with Century. the uniform block with preservation of large branches of an aortic arch and upper vena cava. The vascular system of a transplant is perfused the cooled solution of Polyglucinum with heparin. Transplantation of the block a thymus gland — a breast is made to the femoral area. For this purpose in a femoral triangle bare a vascular bundle and impose a number of an anastomosis. The deep artery of a hip is sewed from one of branches of an aortic arch of a transplant (with the general carotid artery or a brachiocephalic trunk), and the central end of a big saphena is sewed with an upper vena cava of a transplant. Operation is carried out under the general anesthesia. Change of the block a thymus gland — a breast is shown to children at immunological insufficiency with an ataxy teleangiectasia and other forms of deficit T-system of immunity.

Transplantation of suspension of cells of Century. it was ineffective.

The clinicodiagnostic characteristic of the main anomalies, damages of a thymus and diseases connected with disturbance its functions (table)

  • are united In this group diseases, the general for which is existence of a uniform releaser of pathological

changes, i.e. increase in level of autoantibodies against various antigens responsible for an observed clinical picture which variability, apparently, is connected with various action of autoimmune antibodies. Probably dysfunction of the thymus controlling products of autoantibodies is the cornerstone of these diseases.

Bibliography:

Ageev of A. K. Gistopatologiya of a thymus of the person, L., 1973, bibliogr.;

Burnett F. M. Cellular immunology, the lane with English, M., 1971, bibliogr.; Vasya of l the Yeysk S. S., L about-pukhin Yu. M. and Petrov R. V. 0 fetoprotein as a timuszavisimy factor at the person, Ontogenesis, t. 3, No. 2, page 205, 1972, bibliogr.; Vorobyova E. A. Lymphatic system of a thymus of the person, Arkh. annate., gistol, and emb-riol., t. 41, No. 9, page 60, 1961; r at N-t of e of N to about E. V. Timus and carcinogenesis, Genetic aspect of a problem, Usp. sovr, biol., t. 75, century 2, page 278, 1973, bibliogr.; Kuznetsov I. D. and Rozensht-r and at x L. S. Radiodiagnosis of tumors * mediastinums, M., 1970; Lopukhin Yu. M. and d the river Kliniko-immunologi-cheskoye studying and transplantation of a thymus gland at Louis Bar syndrome, Zhurn, a neuropath, and psikhiat., t. 71, century 10, page 1466, 1971, bibliogr.; Miller J. idukorp. Biology of a thymus gland, the lane with it., * M., 1967, bibliogr.; Romantsev E. T., etc. Radiation biochemistry of a thymus gland, M., 1972; Bernatz Ph., Harrison E. a. With 1 a g e t t O. Thymoma, J. thorac. car-diovasc. Surg., v. 42, p. 424, 1961; Berry C. L. The neonatal thymus and immune paresis, Proc. roy. Soc. Med., v. 61, p. 867, 1968; B 1 an u J. N. The dynamic behavior of Hassall's corpuscles and the transport of particulate matter in the thymus of the guinea-pig, Immunology, v. 13, p. 281, 1967; Burnet F.M. Role of the thymus and related organs in immunity, Brit, med. J., v. 2, p. 807, 1962; Burnet F. M of a. M and with k and at I. R. Lymphoepithe-lial structres and autoimmune disease, Lancet, v. 2, p. 1030, 1962; Castleman B. Tumors of the thymus gland, Washington, 1955; Contemporary topics in immunobiology, Thymus dependency, ed. by A. J. S. Davies a. R. L. Carter, v. 2, N. Y., 1973; Dameshek W. The thymus and lymphoid proliferation, Blood, v. 20, p. 629, 1962; Escande J. - P. e t Cambier J. Le thymus, Rev. Prat. (Paris), t. 20, p. 3717, 1970; Greenwood R. D. a. o. Swiss type agammaglobulinemia in the United States, Amer. J. Dis. Child., v. 121, p. 30, 1971; Havard C. W. H. Clinical disorders associated with changes in the thymus, Trans, med. Soc. Lond., v. 86, p. 87, 1970, bibliogr.; Hirokawa K. Electron microscopic observation of the human thymus of the fetus and the newborn, Acta path, jap., v. 19, p. 1, 1969; Metcalf D. The thymic origin of the plasma lymphocytosis stimulating factor, Brit. J. Cancer, v. 10, p. 442, 1956; it, The thymus, B., 1966, bibliogr.; Miller J. F. Immunological function of the thymus, Lancet, v. 2, p. 748, 1961; it, Endocrine function of the thymus, New Engl. J. Med., v. 290, p. 1255, 1974; P i n k e 1 D. Ultrastructure of human fetal thymus, Amer. J. Dis. Child., v. 115, p. 222, 1968; Schonfelder M. u. a. Immunologische, histologische, histoche-mische Befunde bei Myastenia gravis vor und nach Thymektomie, Z. ges. inn. Med., S. 757, 1969; Seybold W. D. a. o. Tumors of thymus, J. thorac. Surg., v. 20, p. 195, 1950; Souadjian J. Y., S i 1-v e r s t e i n M. N. and. T i t u s J. L. Morphologic studies of the thymus in human neoplasia, Cancer (Philad.), v. 23, p. 619, 1969; Stutman O. Good R. A. Duration of thymic function Ser. Haematol., v. 7, p. 505, 1974, bibliogr.; Thymic hormones, ed. by T. D. Luckey, Baltimore a. o., 1973.


L. V. Kovalchuk; B. V. Alyoshin, A. F. Sorokin, AA. 3. Yusfina (An., gist., embr.), T.E. Ivanovskaya (stalemate. An.), M. I. Kuzin, A. I. Pirogov (PMC.), N. A. Panov (rents.), B. A. Tabolin (ped.), authors of the tab. L. V. Kovalchuk, V. A. Svetlov, A. M. Hilkin.

Яндекс.Метрика