Lymph vessels, Lymph nodes
Lymph nodes, located mainly in the neck, armpits, and pelvic area, are the system that battles against infection, and are named after their locations in the body. For example, the lymph nodes at the arm are called axial and brachial. Lymph nodes are connected to one another by lymphatic vessels. Lymph nodes acts as the pockets of lymph that removes foreign material such as bacteria, viruses, and cancerous cells from the lymph. They vary in size from microscopic to about 0.16 inch (0.394 cm) in diameter.
Lymphatic vessels are made of single-cell epithelial layers that drain fluid away from tissue and toward the lymph nodes and eventually to the heart. Lymphatic fluid usually returns to the circulation within 24 hours.