Organs of the immune system

The immune system can be distinguished by function as the:
Primary Lymphoid organs:
  • Only after a lymphocyte has matured a primary lymphoid organ is the cell immune competent.
  • In mammals, T-cells mature in the "Thymus" and B-cells mature in the "Bone marrow” (in Bursa of Fabricus in birds).
  • There are TWO cells in the Primary Lymphoid Organs – Thymus and Bone Marrow.
Secondary lymphoid organs


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