In the context of primary lymphoid organs, which hormone is primarily secreted by the thymus gland to support T-lymphocyte maturation?

• A. Thymosin
• B. Erythropoietin (EPO)
• C. Cortisol
• D. Melatonin

Answer: (A)

Verified step by step guidance

1. Understand the role of primary lymphoid organs: These organs are where lymphocytes mature. The thymus gland is a primary lymphoid organ responsible for the maturation of T-lymphocytes (T cells).
2. Identify the hormone secreted by the thymus gland: The thymus produces a hormone that supports the development and maturation of T-lymphocytes, which is essential for the adaptive immune response.
3. Recall the specific hormone involved: The hormone secreted by the thymus to aid T-cell maturation is called thymosin.
4. Differentiate thymosin from other hormones listed: Erythropoietin (EPO) is involved in red blood cell production, cortisol is a stress hormone from the adrenal cortex, and melatonin regulates sleep cycles, so these are not related to T-cell maturation.
5. Conclude that thymosin is the hormone primarily secreted by the thymus gland to support T-lymphocyte maturation.