Lymph nodes are secondary lymphoid organs that range in size from a few millimeters to about 1-2 cm long. They are enclosed in a fibrous capsule and contain an outer cortex and inner medulla. The primary function of lymph nodes is to filter lymph and fight infection using lymphocytes including B and T cells that reside within.

1. Lymph node
 In the lymphatic system the lymph node is a secondary lymphoid organ.
 A lymph node is enclosed in a fibrous capsule and is made up of an outer cortex and an
inner medulla.
 Lymph nodes are kidney or oval shaped and range in size from a few millimeters to about
1–2 cm long.
 The primary function of lymph nodes is the filtering of lymph to identify and fight
infection.
 In order to do this, lymph nodes contain lymphocytes, a type of white blood cell, which
includes B cells and T cells. These circulate through the bloodstream and enter and reside
in lymph nodes.
 Lymph nodes are important for the proper functioning of the immune system, acting as
filters for foreign particles and cancer cells.
 Lymph nodes also have clinical significance. They become inflamed or enlarged in
various diseases which may range from trivial throat infections, to life-
threatening cancers.