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

Options

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

Explanation

To determine which endocrine gland stores its secretion in the extracellular space before discharging it into the blood, we can analyze the options provided:

1. **Testis**: The testis is responsible for producing testosterone, which is released directly into the bloodstream. It does not store its secretion in an extracellular space.

2. **Thyroid**: The thyroid gland produces hormones such as thyroxine. It stores these hormones in a colloid, which is an extracellular space within the thyroid follicles. When needed, the hormones are released into the bloodstream.

3. **Pancreas**: The pancreas produces insulin and other hormones. It releases these hormones directly into the blood without storing them in an extracellular space.

4. **Adrenal**: The adrenal glands produce hormones like adrenaline. Similar to the pancreas and testis, these hormones are released directly into the bloodstream without prior storage in an extracellular space.

Based on this analysis, the only gland that stores its secretion in the extracellular space before discharging it into the blood is the **thyroid gland**.

**Final Answer**: The correct answer is option 2, the thyroid gland.