SBA — Single Best Answer · Review
Question 606
Immunology → General
Classification
Question
SSBAQuestion Header
Which pair consists entirely of primary lymphoid organs?
Question Stem
Select the single best answer.
Options
A
Thymus and bone marrow
B
Spleen and lymph nodes
C
Thymus and spleen
D
Bone marrow and lymph nodes
E
Spleen and bone marrow
Explanation
Primary lymphoid organs are sites where lymphocytes mature and become antigenically committed. In humans, T lymphocytes mature in the thymus and B lymphocytes arise and mature in bone marrow. Spleen and lymph nodes are secondary lymphoid organs.
Option Validity
B) Both spleen and lymph nodes are secondary lymphoid organs.
C) The thymus is primary, whereas the spleen is secondary.
D) Bone marrow is primary, whereas lymph nodes are secondary.
E) The spleen is secondary, whereas bone marrow is primary.
Further Reading
Saxena MRCOG-1 Basic Sciences — Immunology: Organisation of the Immune System, printed page 208.