Introduction

In humans one distinguishes between primary and secondary lymphatic organs. In the primary lymphatic organs the lymphocytes mature to become immunocompetent cells and emigrate into the secondary lymphatic organs. There they are responsible for mounting the specific defense of the body.

To the primary lymphatic organs belong:

• Thymus
• Bone marrow

To the secondary lymphatic organs belong:

• Lymph nodes
• Tonsils
• Lymph follicles of the mucous membranes
• White pulp of the spleen