Home to connective tissues!
With blood, lymph is an important fluid connective tissue component involved in body defense. Remember, lymph forms from the plasma and interstitial fluids draining from capillary beds. You will note the flow of lymph from these sites is directed through lymph nodes.
Lymph nodes are best described as filters! Fluid draining from interstitial spaces contains solutes, cell fragments, and phagocytic cells that result from inflammatory events. Within the lymph nodes, phagocytic cells engulf and remove the cellular debris. Soluble proteins and other antigenic components that might arrive via the lymph flow can be monitored by cells in residence within lymph nodes. Most of these are lymphocytes.
You will learn more about immune reactions later. For now, remember lymph nodes as important sites where your body stages and mobilizes defenses that can include antibodies or specific "cytotoxic" T-lymphocytes. The fluid connective tissue component flowing through these tissues is lymph.
Here is a view of a lymph node. Look closely and you can see two spherical areas where cell density is higher. These are centers where lymphocytes are mobilizing. I've encircled them here if you have difficulty seeing them.
A closer view of the lymph node shows the high density of cells here. Most of these cells are lymphocytes or antibody producing plasma cells. At high magnification, the cells can be seen occupying space between reticular fibers.
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