Which of the following statements given below is/are correct?
I. Secondary lymphoid organs include lymph nodes, spleen, and small masses of lymph tissue such as Peyer’s patches, appendix, and tonsils.
II. The secondary lymphoid organs serve as the sites where lymphocytes interact with antigens.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both statement I and statement II are correct.
Lymphoid organs are where lymphocytes arise, mature and multiply. In the primary lymphoid organs (bone marrow and thymus) immature lymphocytes become antigen-sensitive. They then move to the secondary lymphoid organs.
I. Secondary lymphoid organs include lymph nodes, spleen, and small masses of lymph tissue such as Peyer’s patches, appendix, and tonsils. — True. The spleen, lymph nodes, tonsils, Peyer’s patches of the small intestine and the appendix are all secondary lymphoid organs.
II. The secondary lymphoid organs serve as the sites where lymphocytes interact with antigens. — True. In these organs the lymphocytes meet the antigen, and then multiply to become effector cells.
NCERT Extract:
Immune System in the Body – “… After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix. The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells. The location of various lymphoid organs in the human body is shown in Figure 7.5. The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced.”