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Translated from Russian to English - www.onlinedoctranslator.com Redbone marrow (BMC)• Thymus Erythrocytes, platelets, granulocytes, B-lymphocytes and precursors of T-lymphocytes are formed in the RMC Thymus is the central organT-lymphopoiesis ContainsSKK and differentials hematopoietic cells erythroid,granulocyticand megakaryocytic series, as well as precursors of B- and T-lymphocytes. Stroma bone marrow is reticular connective tissue (microenvironment for hematopoiesis). Elements of the microenvironment also include osteogenic, fatty, adventitial, endothelial cells and macrophages Perform mechanical function, secrete components of the main substance precollagen,glycosaminoglycans,p roelastin And microfibrillar protein and are involved in the creation of hematopoietic microenvironment Called stem cells of supporting tissues, osteoblasts and their precursors.Osteogenic cells are part of end osta and may be located in the bone marrow cavities. Osteogenic cells are also capable of producing growth factors, inducing ancestral hematopoietic cells in their locations to proliferation and differentiation. (fat cells) are permanent elements of the bone marrow. Adventitial cells accompany blood vessels and cover more than 50% of the outer surface sinusoidal capillaries. Influenced hemopoietins (erythropoietin) and other factors, they are able to contract, which promotes the migration of cells into the bloodstream. Vessels bone marrow take part in the organization of the stroma and hematopoietic processes, synthesize type IV collagen,hematopoietins. Endotheliocytes, forming walls sinusoidal capillaries, are in direct contact with hematopoietic and stromal cells due to a discontinuous basement membrane. Richly so somes and phagosomes.Macrophages with the help of their processes, penetrating through the walls of the sinuses, they capture an iron-containing compound from the blood stream (transferrin) and then pass it on to develop in gerythroid cells for building heminova parts of hemoglobin. are located in close contact with the sinuses so that the peripheral part of their cytoplasm penetrates into the lumen of the vessel through the pores. The separation of cytoplasmic fragments in the form of platelets (blood platelets) occurs directly into the bloodstream. OutsideThe gland is covered with a connective tissue capsule; septa extend inward from it, dividing the gland into lobules. In each lobule there arecorticalAndcerebralsubstance. The basis (stroma) of the organ is epithelial tissue, consisting ofprocesscells – epithelioreticulocytes(make up a whole network, clinging to each other with shoots) In addition to epithelial cells, there are supporting cells (macrophages and dendritic cells). They contain products of the main complex histo compatibility, secrete growth factors (dendritic cells) that influence the differentiation of T-lymphocytes. More dark, since the peripheral part of the thymus lobules contains large numbers of T lymphocytes. IN subcapsular the cortical zone contains large lymphoid cells -T lymphoblasts(4-5%), migrated here from the bone marrow. Thisconversion of T lymphocyte precursors to Tlymphoblasts. Proliferation - this is reproductionTlymphoblaststhrough mitosis. Antigen-independent differentiation- this is differentiation with a small amountantigens. IN This barrier consists of 5 components: 1) capillary endothelium; 2) their basement membrane; 3)pericapillarya fluid-filled space where macrophages and lymphocytes are located; 4) basement membrane of the epithelial stroma; 5) cells of the epithelial stroma It has lighter color, because Compared to the cortex, it contains fewer lymphocytes. Lymphocytes in this zone are recycling pool (a large group of cells that, after circulating in the blood, can return to the medulla) of T lymphocytes and can enter and exit the blood stream through post-capillary venules. Quantity mitotically There are approximately 15 times fewer dividing cells in the medulla than in the cortex. In the middle part of the medulla there are layered epithelial taurus-taurus Hassalya. They are formed by concentrically layer reticulocytes, the cytoplasm of which contains large vacuoles, keratin granules and bundles of fibrils. The number of these bodies in humans increases with age. Thymus reaches maximum development in early childhood. In the period from 3 to 18 years, stabilization of its mass is noted. At a later time, reverse development of the thymus occurs. This is accompanied by a decrease in the number of lymphocytes, especially in the cortex, the appearance of lipid inclusions in connective tissue cells and the development of adipose tissue. Layered epithelial bodies persist much longer. In rare cases, the thymus does not undergo age-related involution. This is usually accompanied by a deficiencyglucocorticosteroidsadrenal cortex. Such people are characterized by reduced resistance to infections and intoxications. The risk of developing tumors especially increases. This temporary hypotrophy of the thymus under the influence of unfavorable factors (stress, starvation, infection, etc.). The thymus is involved instress reactionsalong with the adrenal glands. An increase in the amount of adrenal cortex hormones in the body, primarily glucocorticosteroids, causes very fast and strong accidental involution of the thymus. After the cessation of adverse factors, restoration of the thymus occurs due tosubcapsular zones. Are developingfrom mesenchyme (8-10 weeks of embryogenesis). Are locatedalong the lymphatic vessels. Haveround or beanshaped. 1)protective(barrier) – lymph, flowing through the node, is cleansed by macrophages; 2)hematopoietic–lymphocytopoiesis when the antigen enters the lymph. 3)immunobiological- pulpy cords B-lymphocytes, strongly activated by antigen and T-lymphocytes, turn 80% into plasma cells that produce antibodies, 4)depositing- lymph depot. flowing throughlymph nodes, lymph is cleared of foreign particles and antigens by 95-99%, from excess water, proteins, fats, and is enriched with antibodies and lymphocytes. Lymph nodes are covered with a connective tissue capsule, from which trabeculae extend deeper. On the concave surface of the node there is a gate (an artery, nerves enter, veins exit, and an efferent lymph vessel). Bringers lymph vessels enter from the opposite convex side. The stroma of the nodes is represented by reticular tissue - a network of reticular cells, collagen and reticular fibers, as well as macrophages andantigenpresenting cells. The parenchyma of the nodes is represented by lymphoid cells. Occurs in the lymph nodes antigen-dependent proliferation and differentiation of T and B lymphocytes intoeffector(active) cells, as well as the formation of T- and B-memory cells. Big part of the cortical layer and medullary cords are made up of B-lymphocytes (B-zone), and paracortical- the thymus-dependent zone contains mostly T-lymphocytes (T-zone). In the center of the lymph nodes there is a light center (germinative (because they multiplyB lymphoblasts) and reactive (because a reaction occurs between macrophages and antigens). Where do B lymphocytes come from to the cortical zone? They come here from the bone marrow through the bloodstream. And then in lymph node they are exposed to antigens phagocytosed macrophages or retained by dendritic cells (see below) and lymphakines,allocatedT-helpers. Under the influence of all these influences, B lymphocytes blast transformation, proliferation and antigendependent differentiation T-zone IN paracortical zone where T cells proliferate and differentiate into effector cells (killer cells, helper cells,suppressors). Post-capillary venules paracortical zones are the site of penetration of circulating T- and Blymphocytes into the lymph node B-zone From nodules and paracortical zones inside the l/node, into its medulla, the brain cords extend,anastomosing between themselves. It is based on reticular tissue, in the loops of which there are Blymphocytes,plasma cells and macrophages. This is where maturation happens.plasma cells. Inside the medullary cords there are blood vessels and capillaries containing pores in the endothelium. The outside of the cords are cover edendothelial-like reticular cells lying on bundles of reticular fibrils and forming the wall of the sinuses. Spaces, limited by capsuleand trabeculaeon the one hand, and nodules and medullary cords, on the other, are called sinuses, which are, as it were, a continuation of the afferent lymphatic vessels. Distinguish 1-subcapsular(marginal sinus), located between the capsule and nodules, 2-perinodular sinuses passing between the nodules and trabeculae, 3-brain sinuses bounded by trabeculae and medullarycords 4-gate sinus, which is located in the region of the hilum of the lymph node. Sinuses act as protective filters