Hormone melatonin is secreted by

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the source of the hormone melatonin.

2. **Reviewing the Options**: The options provided are:
- A) Adrenal
- B) Thymus
- C) Pituitary
- D) Pineal

3. **Analyzing Each Option**:
- **Adrenal Gland**: This gland is located on top of the kidneys and is divided into two parts: the adrenal cortex and adrenal medulla. It primarily secretes hormones like glucocorticoids, mineralocorticoids, adrenaline, and noradrenaline. Melatonin is not secreted by this gland.
- **Thymus Gland**: This gland is involved in the immune system, specifically in the development of T lymphocytes. It secretes thymosins, not melatonin. Therefore, this option is incorrect.
- **Pituitary Gland**: Known as the master gland, it regulates other endocrine glands and secretes various hormones, but it does not produce melatonin. Thus, this option is also incorrect.
- **Pineal Gland**: This small gland is located in the dorsal part of the forebrain and is responsible for the secretion of melatonin, especially in response to darkness. This makes it the correct answer.

4. **Conclusion**: Based on the analysis, the hormone melatonin is secreted by the **pineal gland**.

**Final Answer**: The hormone melatonin is secreted by the **pineal gland**.

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