Normal lymph node. Light micrograph of a section through a healthy lymph node. Lymph nodes are kidney-shaped organs into which the fluid from body tissues drains and is filtered. The nodes are packed with white blood cells that destroy disease-causing microorganisms within the fluid. The granular appearance of the tissue is caused by the presence of thousands of lymphocyte white blood cells. Magnification: x35, when printed 10 centimetres wide.