Which one of the following endocrine glands stores its secretion in the extracellular space before discharging in into the blood?

Options

A. Testes
B. Pancreas
C. Thyroid
D. Adrenal.

Answer

To answer the question "Which one of the following endocrine glands stores its secretion in the extracellular space before discharging it into the blood?", we will analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for an endocrine gland that stores its secretion in the extracellular space before it is released into the bloodstream.

2. **Analyzing Option A: Testes**:
- The testes are the primary male sex organs that produce testosterone.
- Testosterone is secreted directly into the blood and does not involve storage in the extracellular space.
- **Conclusion**: Not the correct answer.

3. **Analyzing Option B: Pancreas**:
- The pancreas functions as both an endocrine and exocrine gland.
- It secretes insulin (an endocrine function) directly into the blood and digestive enzymes (an exocrine function) through ducts.
- Insulin is not stored in the extracellular space before being released.
- **Conclusion**: Not the correct answer.

4. **Analyzing Option C: Thyroid**:
- The thyroid gland is located in the neck and produces the hormone thyroxine.
- It is known to store thyroxine in the extracellular space (specifically in the colloid of the thyroid follicles) before it is released into the bloodstream.
- This matches the requirement of the question.
- **Conclusion**: This is the correct answer.

5. **Analyzing Option D: Adrenal**:
- The adrenal glands are located above the kidneys and produce various hormones including glucocorticoids and adrenaline.
- These hormones are secreted directly into the blood without prior storage in the extracellular space.
- **Conclusion**: Not the correct answer.

### Final Answer:
The correct answer is **Option C: Thyroid**.

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