Talk:SH Lecture - Lymphatic Structure and Organs
Anatomy of the Human Body. 1918
Henry Gray (1821–1865).
THE LYMPHATIC SYSTEM consists (1) of complex capillary networks which collect the lymph in the various organs and tissues; (2) of an elaborate system of collecting vessels which conduct the lymph from the capillaries to the large veins of the neck at the junction of the internal jugular and subclavian veins, where the lymph is poured into the blood stream; and (3) lymph glands or nodes which are interspaced in the pathways of the collecting vessels filtering the lymph as it passes through them and contributing lymphocytes to it. The lymphatic capillaries and collecting vessels are lined throughout by a continuous layer of endothelial cells, forming thus a closed system. The lymphatic vessels of the small intestine receive the special designation of lacteals or chyliferous vessels; they differ in no respect from the lymphatic vessels generally excepting that during the process of digestion they contain a milk-white fluid, the chyle.
Lymphatic Vessels.—The lymphatic vessels are exceedingly delicate, and their coats are so transparent that the fluid they contain is readily seen through them. They are interrupted at intervals by constrictions, which give them a knotted or beaded appearance; these constrictions correspond to the situations of valves in their interior. Lymphatic vessels have been found in nearly every texture and organ of the body which contains bloodvessels. Such non-vascular structures as cartilage, the nails, cuticle, and hair have none, but with these exceptions it is probable that eventually all parts will be found to be permeated by these vessels.
Lymph Glands (lymphoglandulæ).—The lymph glands are small oval or bean-shaped bodies, situated in the course of lymphatic and lacteal vessels so that the lymph and chyle pass through them on their way to the blood. Each generally presents on one side a slight depression—the hilus—through which the bloodvessels enter and leave the interior. The efferent lymphatic vessel also emerges from the gland at this spot, while the afferent vessels enter the organ at different parts of the periphery. On section (Fig. 597) a lymph gland displays two different structures: an external, of lighter color—the cortical; and an internal, darker—the medullary. The cortical structure does not form a complete investment, but is deficient at the hilus, where the medullary portion reaches the surface of the gland; so that the efferent vessel is derived directly from the medullary structures, while the afferent vessels empty themselves into the cortical substance.
