Henry Gray (18251861). Anatomy of the Human Body. 1918.
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 depressionthe hilusthrough 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 colorthe cortical; and an internal, darkerthe 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.
Structure of Lymph Glands.A lymph gland consists of (1) a fibrous envelope, or capsule, from which a frame-work of processes (trabeculæ) proceeds inward, imperfectly dividing the gland into open spaces freely communicating with each other; (2) a quantity of lymphoid tissue occupying these spaces without completely filling them; (3) a free supply of bloodvessels, which are supported in the trabeculæ; and (4) the afferent and efferent vessels communicating through the lymph paths in the substance of the gland. The nerves passing into the hilus are few in number and are chiefly distributed to the bloodvessels supplying the gland.
The capsule is composed of connective tissue with some plain muscle fibers, and from its internal surface are given off a number of membranous processes or trabeculæ, consisting, in man, of connective tissue, with a small admixture of plain muscle fibers; but in many of the lower animals composed almost entirely of involuntary muscle. They pass inward, radiating toward the center of the gland, for a certain distancethat is to say, for about one-third or one-fourth of the space between the circumference and the center of the gland. In some animals they are sufficiently well-marked to divide the peripheral or cortical portion of the gland into a number of compartments (so-called follicles), but in man this arrangement is not obvious. The larger trabeculæ springing from the capsule break up into finer bands, and these interlace to form a mesh-work in the central or medullary portion of the gland. In these spaces formed by the interlacing trabeculæ is contained the proper gland substance or lymphoid tissue. The gland pulp does not, however, completely fill the spaces, but leaves, between its outer margin and the enclosing trabeculæ, a channel or space of uniform width throughout. This is termed the lymph path