Is The Lymphatic System In Other Animals
The lymphatic organization is constituted by the lymphatic vessels and the lymphoid organs (lymphatic nodules, lymphatic nodes, spleen and thymus).
Lymphatic vessels
Lymphatic vessels incorporate and transport a liquid known equally lymph, which is collected from the tissues and organs of the body and released into large veins. Modest diameter lymphatic vessels, or lymphatic capillaries, are mainly found in the loose connective tissue of the dermis and in the intestine mucosa. These ducts are closed at one end, whereas the other fuses with other capillaries to course larger ducts known as lymphatic vessels. In turn, lymphatic vessels bring together to one some other and form larger vessels. Finally, the largest lymphatic vessels release the lymph into the large veins located in the neck, betwixt the jugular and subclavian veins.
Lymphatic capillaries are fabricated up of endothelium and a discontinuous basal lamina that makes possible college permeability than in most blood capillaries. And so, lymphatic capillaries are more efficient gathering fluid from tissues. This fluid becomes the lymph, which is a solution with ions and proteins. In the lymphatic nodes and nodules, lymph components meet the cells of the immune system.
Lymphatic vessels contain layers of connective tissue and smooth muscle cells, more adult equally the diameter gets larger. Similar in veins, these vessels have valves to prevent the lymph reflux. Because the movement of the lymph through the vessels is not pumped by the heart, lymph is propelled past the movements of the trunk and of internal organs, i.east., the lymph is driven forrad by the muscles of the body.
Lymphatic nodules
In the lamina propria of the intestine, urogenital and respiratory tracts, at that place are aggregates of lymphatic tissue mostly containing lymphocytes, organized effectually lymphatic vessels, and non covered past a connective sheathing. These structures are known as lymphatic nodules. They are distributed through the body and altogether form the so-called diffuse lymphatic tissue. Lymphatic nodules are found in strategic locations of the body to be the get-go defenders against pathogens so that they participate in the early allowed system response. Lymphocytes that produce antibodies and eosinophiles are abundant in lymphatic nodules. Reticular connective tissue conatining reticular cells and fibers form the stroma of lymphatic nodules.
Structurally, lymphatic nodules are composed of a germinative heart where lymphocytes proliferate and differentiate into plasmatic cells for synthesize and release antibodies. Actually, the presence of a germinative center ways that an immune response is in progress. Surrounding the germinative heart, in that location is a peripheral zone, known as curtain or corona (cap), with smaller lymphocytes. Also the location in the mucosas, lymphatic nodules are abundant in the appendix, in the tonsils and in the Peyer's patches of the ileum.
Lymphatic node
Lymphatic nodes are kidney-similar structures covered by a layer of connective tissue or capsule. They are located in the path of lymphatic vessels, between the tissues and the large veins. The size of lymphatic nodes ranges from a few millimeters to two centimeters. They are abundant in the axilla, inguinal region and mesenteries.
Lymphatic nodes comprise connetive and reticular tissues organized in supporting structures. The external capsule is dense connective tissue that sed out projections toward the interior of the node. These proyeccions are known as trabeculae and class the main support framework of the lymphatic node. Internally, there is reticular connective tissue, with cells and reticular fibers, that concur node tissue. Both, trabeculae and reticular tissue proceed the spatial arrangement of the node and suppport the lymphatic cells. In i point of the surface of the node there is the hilio, where the efferent lymphatic comes out the node, and claret vessels enter and leave the node
The lymphatic node is divided into an outer role or cortex and an inner role or medulla. In the outer cortex, B lymphocytes are organized in nodules o follicles, that can be either primary follicles (with a germinative center) or secondary follicles (without germinative center). Deeper to the follicles, there is a region known as paracortex, where T helper lymphocytes are arable.
The key part of the lymphatic node is known equally medulla. It contains lymphatic tissue organized in the and then-chosen medullary cords separated past medullary sinuses. In that location is also a supporting scaffold of reticular tissue. Lymphatic tissue is mainly constituted by lymphocytes, macrophages and plasma cells.
Fiftyymph filtration occurs while lymph goes through ducts and sinuses in lymphatic nodes. First, lymph enters the lymphatic node crossing the capsule through the supbcapsular, marginal and cortical sinuses. From hither, lymph is gathered past the trabecular sinuses and after that by the medullary sinuses. The endothelium of the these sinuses is discontinuous in the areas where it is in contact with lymphatic tissue. From the medullary sinuses, lymph is collected into the efferent lymphatic vessel that quits the lymphatic node past the hilium.
50ymphatic nodes are major places for phagocytosis and for the start of the immune response. Lymph transports migrant dendritic cells to lymphatic nodes. These cells tin can initiate the allowed response, but resident dendritic cells located in the cortex of the nodes tin initiate the response too. Both are antigen presenting cells and induce the activation of B lymphocytes in the transition zone between cortex and medulla. Activated lymphocytes migrate to primary nodes and proliferate to form the germinative centers, so that primary follicles go secondary follicles. These lymphocytes differentiate in retentivity B lymphocytes and plasma cells. Both move to the medullary region of the node. Later, most of the retention B lymphocytes quit the lymphatic node and colonize other secondary lymphatic organs to produce clones. About 90 % of plasma cells also leave the lymphatic nodes and go to bone marrow to produce antibodies.
Thymus
Thymus is a lobed organ found in a higher place the center and before the big claret vessels. It develops from the pharynx endoderm. The primary role of thymus is done in the menstruum included between nativity and puberty, and is a identify where T lymphocytes mature. Afterward puberty, the thymus lymphatic tissue is replaced by adipose tissue.
Thymus is covered by a capsule of connective tissue. In some parts, this layer protrudes inward dividing the organ in uncompleted compartments known as lobes. Thymus lobes are constituted of thymic parenchyma, which can be divided in 2 parts: cortex and medulla. Cortical parenchyma contains many developing T lymphocytes, likewise known every bit thymocytes, macrophages and epithelial-reticular cells. In the medulla in that location are T lymphocytes as well, but there are more loosely distributed. Medulla appears more articulate after general staining.
Blood vessels enter the thymus through trabeculae. These vessels have a sheath of connective tissue. T lymphocytes practice not contact straight with claret considering there is a barrier, known equally claret-thymus barrier, made upwardly of endothelium, macrophages and epithelial-reticular cells.
Spleen
The largest lymphatic organ is the spleen. It performs hematopoietic and allowed functions. Spleen is heavily irrigated by the claret system, which has two functions: mechanical and allowed filtration. Information technology contains many lymphocytes, macrophages, reticular cells (which form a kind of cyberspace), as well as not-cellular spaces and vascular ducts.
Southpleen is wrapped past a capsule of dense connective tissue that send trabeculae to the interior of the organ. This connective tissue contains myofibroblasts with the ability of contraction. The spleen tin can store big amount of erythrocytes, which are released again to the main vessels by the contractions of myofibroblasts.
The spleen pulp, or spleen parenchyma, is the inner part of the organ, which is not connective tissue. There are two types: white and red. White lurid contains many lymphocytes arranged around the central artery, forming a sheath known as periarterial lymphatic sheath (PALS). The cerise pulp contains many erythrocytes and vein sinuses.
Source: https://mmegias.webs.uvigo.es/02-english/2-organos-a/guiada_o_a_06linfatico.php
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