Figure 24-16. A simplified drawing of a human lymph node.

Figure 24-16A simplified drawing of a human lymph node

B cells are primarily clustered in structures called lymphoid follicles, whereas T cells are found mainly in the paracortex. Both types of lymphocytes are attracted by chemokines to enter the lymph node from the blood via postcapillary venules. They then migrate to their respective areas, attracted by different chemokines. If they do not encounter their specific antigen, both T cells and B cells then enter the medullary sinuses and leave the node via the efferent lymphatic vessel. This vessel ultimately empties into the bloodstream, allowing the lymphocytes to begin another cycle of circulation through a secondary lymphoid organ (see Figure 24-14).

From: Lymphocytes and the Cellular Basis of Adaptive Immunity

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.