Lymph capillaries are thin-walled vessels, arranged in a network that permeates virtually all the tissues of the body.

The fluid they collect drains into larger lymph vessels that have a large number of valves. These eventually empty into the subclavian veins at the root of the neck.

The spleen is an organ that contains a large quantity of lymphoid tissue and, like the lymph nodes, is able to eliminate foreign particles. Its main functions are to:

• filter the blood
• destroy worn out red blood cells
• produce some white blood cells.