Lymphatic capillaries consist of vessels lined with endothelial cells, which begin as blind-ended tubules or saccules in most tis sues of the body Endothelium is attenuated and usually lacks a continuous basal lamina. . Lymphatic vessels of large diameter resemble veins in their struc ture but lack a clear-cut separation between layers. Valves are more numerous in lymphatic vessels. Smooth muscle cells in the media layer engage in rhythmic contraction, pumping lymph toward the venous system. Smooth muscle is well-developed in large lymphatic ducts.

Circulation of lymph is slower than that of blood, but it is nonetheless an essential process. It has been estimated that in a single day, 50 % or more of the total circulating protein leaves the blood circulation at the capillary level and is recaptured by the lymphatics.

Distribution of lymphatics is ubiquitous with some notable excep tions, including epithelium, cartilage, bone, central nervous sys tem, and thymus.

plasma – плазма

extracellular – внеклеточный

aqueous – водный

solution – раствор

proteins – белки

inorganic – неорганический

salts – соли

organic – органический

albumin – альбумин

globulins – глобулины

alpha – альфа

beta – бета

gamma – гамма

fibrinogen – фибриноген

lymphatic – лимфатический

vessel – сосуд

endothelium – эндотелий

circulation – кровообращение

lymph – лимфа

ubiquitous – вездесущий

notable – известный

21. Hematopoietic tissue. Erythropoiesis

Hematopoietic tissue is composed of reticular fibers and cells, blood vessels, and sinusoids (thin-walled blood channels).