Name the primary and secondary lymphoid organs.

Explanation

Lymphoid organs. These are the organs where origin and/or maturation and proliferation of lymphocytes takes place.
Lymphoid organs may be:
1. Primary lymphoid organs. Bone marrow and Thymus, where immature lymphocytes differentiate into antigen-sensitive specific receptor lymphocytes - B-lymphocytes and T-lymphocytes, are called primary lymphoid organs.
2. Secondary Lymphoid Organs. After maturation the lymphocytes migrate to the secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer.s patches of small intestine, appendix.and MALT etc. They provide the sites for the interaction of lymphocytes with antigens and `"produce "//" proliferate"` and differentiate to become effector cells and memory cells.