Lymphatic capillaries
Last reviewed: 23.04.2024
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Lymphatic capillaries (vasa lymphocapilldria) are the initial link - the "roots" of the lymphatic system. They are present in all organs and tissues of the human body, except the brain and spinal cord, their membranes, the eyeball, the inner ear, the epithelial cover of the skin and mucous membranes, cartilage, spleen parenchyma, bone marrow and placenta. Unlike blood capillaries, lymphocapillaries have a larger diameter (from 0.01 to 0.2 mm), uneven contours, lateral protrusions. When combined with each other, they form closed lymphocapillary nets (organs and tissues) in organs and tissues (rete lymphocapillar). The loops of these nets lie in one or several planes, depending on the structure (structure) of the organ in which they are located. The orientation of the capillaries corresponds to the direction of the bundles of connective tissue, in which the lymphatic capillaries overlap. So, in volumetric organs (muscles, lungs, liver, kidneys, large glands, etc.) lymphocapillary nets have a three-dimensional structure. Lymphatic capillaries in them are oriented in different directions, located between structural and functional elements of the organ: bundles of muscle fibers, groups of glandular cells, renal corpuscles and tubules, hepatic lobules. In flat organs (fascia, serous membranes, skin, layers of walls of hollow organs, walls of large blood vessels), lymphocapillary nets are located in one plane parallel to the surface of the organ. In some organs, the network of lymphatic capillaries forms finger-like long blind protrusions (for example, lymphatic sinuses in villi of the small intestine).
The walls of the lymphatic capillaries are constructed from a single layer of endothelial cells. These cells are attached to a number of lying bundles of collagen fibers with the help of beams of the finest fiber-rope (anchor) filaments. Such a connection between collagen fibers and the walls of the lymphatic capillaries promotes the opening of the luminal capillaries, especially in swelling of the tissues in which these capillaries are located. Lymphatic capillaries with valves are considered as lymphatic post-capillaries.
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