nyirokérhálózaton

The nyirokérhálózat, or lymphatic capillary network, is the initial and most finely branched component of the lymphatic vascular system. It is found throughout the body's tissues, permeating nearly every organ and region, with the notable exceptions of the central nervous system, bone marrow, and avascular tissues like cartilage and the cornea. These microscopic vessels are blind-ended tubes, meaning they begin as closed sacs within the interstitial spaces where they collect excess interstitial fluid, also known as lymph.

The walls of lymphatic capillaries are exceptionally thin, composed of a single layer of endothelial cells. These cells overlap loosely, forming flap-like valves that allow interstitial fluid and larger molecules, such as proteins, fats, and pathogens, to enter the capillary. However, these valves prevent the backflow of lymph into the tissue. As the interstitial fluid pressure increases, the valves open, facilitating entry. Once inside, the fluid is called lymph.

The nyirokérhálózat plays a crucial role in maintaining fluid balance by draining excess fluid from tissues and returning it to the bloodstream. It also transports absorbed fats from the digestive system and is a vital part of the immune system, carrying immune cells and foreign substances to lymph nodes for processing and response. The lymphatic capillaries progressively merge to form larger lymphatic vessels, which eventually drain into the venous system.