noun, plural: lymphatic capillaries
The lymphatic system is a biological system that is responsible mainly for the collection and returning of the fluid and proteins into the blood. It is comprised of lymph nodes, lymph vessels, lymphoid tissues, and lymph. The lymph is the clear, slightly alkaline fluid circulating through the lymphatic system. The vessel that is responsible for carrying lymph is the lymphatic vessel or lymphatics. The lymphatics include the lymph capillaries, the contractile lymphatics, and the larger lymph ducts. The lymph capillaries are the beginning of the lymphatic system of vessels. They are thin-walled and are comprised of a single layer of simple squamous epithelial cells. They have a poorly developed basement membrane. The lumen is of variable internal diameter (caliber). The lymph capillaries collect lymph from the interstitial fluid. They drain lymph into the collecting lymphatics that propel lymph towards lymph nodes or towards a lymph duct. The lymph duct, in turn, eventually drains lymph back into the venous circulation through the subclavian veins.
The lymph capillaries are similar to the blood capillaries in terms of the layer of endothelial cells that comprise them. However, the lumen of lymph capillaries has a slightly larger diameter than that of the blood capillaries. Lymph capillaries also have closed ends whereas blood capillaries have a loop structure. This structure is essential in allowing the influx of the interstitial fluid while preventing efflux.
- initial lymphatic
- lymphatic capillary