Lymph node

One of numerous round, oval, or bean-shaped bodies located along the course of lymphatic vessels, varying greatly in size (1–25 mm in diameter) and usually presenting a depressed area, the hilum, on one side through which blood vessels enter and efferent lymphatic vessels emerge for the filtration and trapping of foreign particles and as part of a fully functional immune system

Description
The lymph node as a structure consists of a fibrous capsule and internal trabeculae supporting lymphoid tissue and lymph sinuses; lymphoid tissue is arranged in nodules in the cortex and cords in the medulla of a node, with afferent vessels entering at many points of the periphery. They contain white blood cells which interact with retained foreign bodies and are thus of clinical importance for the immune system. Lymph nodes become inflamed or enlarged in different conditions, ranging from minor ailments, such as a throat infection, to life-threatening conditions, such as cancers. Upon inflammation, biopsy of lymph nodes can be indicative of cancer stage, applicable treatment and prognosis of cancers. More generally, location and condition of affected lymph nodes is characteristic for different kinds of diseases.