Question

The _____1_____ is the main lymphoid organ where all blood cells _____2____ lymphocytes are produced. The_____3_____ is a lobed organ located near the heart and beneath the breastbone. The_____3_____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. Both _____1_____and _____3_____provide micro-environments for the development and maturation of T-lymphocytes.

• A. $\left(1\right) & \left(2\right) & \left(3\right) \\ bonemarrow & including & thymus$
• B. $\left(1\right) & \left(2\right) & \left(3\right) \\ spleen & including & thymus$
• C. $\left(1\right) & \left(2\right) & \left(3\right) \\ thymus & excluding & bonemarrow$
• D. $\left(1\right) & \left(2\right) & \left(3\right) \\ bonemarrow & excluding & spleen$

Answer 1

Answer: (A)

Lymphoid organs are the organs where the origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes. 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. Both bone-marrow and thymus provide micro-environments for the development and maturation of T-lymphocytes.