The posterior pituitary gland is not a 'true' endocrine gland because

Options

A. it is provided with a duct
B. it only stores and releases hormones
C. it is under the regulation of hypothalamus
D. it secretes enzymes

Answer

### Step-by-Step Solution:

1. **Definition of Endocrine Glands**: Endocrine glands are known as ductless glands. They produce hormones and release them directly into the bloodstream without the use of ducts.

2. **Function of the Posterior Pituitary Gland**: The posterior pituitary gland does not produce hormones itself. Instead, it stores and releases hormones that are produced by the hypothalamus.

3. **Hormones Involved**: The two main hormones associated with the posterior pituitary gland are oxytocin and vasopressin (also known as antidiuretic hormone, ADH). These hormones are synthesized in the hypothalamus.

4. **Storage and Release Mechanism**: The posterior pituitary gland acts as a storage site for oxytocin and vasopressin. When needed, these hormones are released into the bloodstream from the posterior pituitary.

5. **Conclusion**: Since the posterior pituitary gland does not produce hormones but only stores and releases them, it is not considered a 'true' endocrine gland. It is regulated by the hypothalamus, which is responsible for the production of the hormones.

### Final Answer:
The posterior pituitary gland is not a 'true' endocrine gland because it does not produce hormones; it only stores and releases hormones (oxytocin and vasopressin) that are produced by the hypothalamus.

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