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Lymph Nodes

Learn the basics of lymph nodes—what they are, what they do and their importance to your body's health and wellbeing.

Review of Lymph Nodes

The lymphatic system plays a key role in the body's immune response, transporting white blood cells to and from the lymph nodes, where they are stored and activated as needed. Lymph nodes are small, bean-shaped structures that can be found throughout the body, particularly in the neck, armpits, and groin. This article will review the histology of lymph nodes and discuss their various functions.


The lymph node is composed of two distinct types of tissue: the cortex and the medulla. The cortex is the outermost layer and is composed of lymphocytes, macrophages, and dendritic cells. These cells are arranged in follicles, which are composed of a network of blood vessels and lymphatic vessels. The medulla is the innermost layer of the lymph node and is composed of reticular cells, which form a mesh-like structure.

The lymphnode is also surrounded by a capsule of connective tissue which helps to anchor the lymph node in place.


The primary function of the lymph node is to filter and store lymphocytes. Lymph nodes also produce antibodies which help to fight off infection and activate the body’s immune response. Additionally, lymph nodes produce cytokines, which are molecules that help to regulate the immune response.

Lymph nodes also act as a site of antigen processing, where antigens are identified and tagged for destruction by the body's immune system. Finally, lymph nodes act as a drainage site, where lymph fluid is filtered and returned to the bloodstream.


Lymph node enlargement is a common symptom of infection and can be caused by a variety of diseases and conditions, including lymphoma, leukemia, and HIV infection. Additionally, lymph nodes can become enlarged if they become blocked or obstructed, often due to a tumor or cancerous growth.

Enlarged lymph nodes can also be caused by autoimmune diseases, such as rheumatoid arthritis and lupus. In these cases, the lymph nodes become swollen and inflamed due to the body’s own immune cells attacking the body’s own tissues.


Lymph nodes play an important role in the body's immune response. They are composed of two distinct tissue types: the cortex and the medulla. The primary functions of the lymph node are to filter and store lymphocytes, produce antibodies, and act as a site of antigen processing. They can become enlarged due to a variety of diseases and conditions, including infection, cancer, and autoimmune diseases.

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