Which of the following glands is large sized at birth but reduces in size with ageing ?

Options

A. Pineal
B. Pituitary
C. Thymus
D. Thyroid

Answer

**Step-by-Step Solution:**

1. **Identify the Glands**: The question asks about glands that are large at birth but decrease in size with age. The glands to consider are the thymus, pituitary, and thyroid.

2. **Understand the Function of the Thymus**: The thymus is a primary lymphoid organ located behind the breastbone. It plays a crucial role in the maturation of T-cells (T-lymphocytes), which are essential for the immune response.

3. **Size of the Thymus at Birth**: At birth, the thymus is relatively large compared to its size in adulthood. This is because the immune system is developing, and T-cells are being produced in large numbers.

4. **Atrophy of the Thymus with Age**: The thymus begins to atrophy (shrink) after puberty. By this time, the production of T-cells decreases, and the thymus's role in the immune system diminishes. As a result, the size of the thymus decreases significantly with age.

5. **Conclusion**: Among the glands mentioned, the thymus is the one that is large at birth but reduces in size as a person ages. This reduction in size is associated with a decrease in immune function, which is why older individuals may have lower immunity.

**Final Answer**: The gland that is large at birth but reduces in size with aging is the **thymus**.

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