Which one of the following lymphoid organ is large at birth but reduces with age?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Thymus
Option (1) Bone marrow — Incorrect. The bone marrow is a primary lymphoid organ where all blood cells, lymphocytes included, are made. It stays at work through life and does not shrink in the way the question describes.
Option (2) Thymus — Correct. The thymus is a primary lymphoid organ where T-lymphocytes mature. It is large at birth and becomes very small by puberty.
Option (3) Spleen — Incorrect. The spleen is a large bean-shaped secondary lymphoid organ. It filters the blood by trapping microorganisms and stores erythrocytes.
Option (4) Peyer’s patches — Incorrect. Peyer’s patches are lymphoid tissue in the lining of the small intestine, part of the mucosa-associated lymphoid tissue (MALT).
NCERT Extract:
Immune System in the Body – “… The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced. The thymus is a lobed organ located near the heart and beneath the breastbone. The thymus is quite large at the time of birth but keeps reducing in size with age and by the time puberty is attained it reduces to a very small size.”