Secondary lymphoid organs are the organs where lymphocytes are activated, encounter antigens, and initiate an adaptive immune response. According to the provided reference, the following are secondary lymphoid organs:
- The lymph nodes
- The spleen
- The tonsils
- Certain tissue in various mucous membrane layers in the body (for instance, in the bowel).
These organs play a crucial role in the immune system's ability to respond to threats.
