Which of the following pass through the hypothalamic neurons and not through the hypophyseal pituitary portal circulation?

Options

A. Oxytocin and vasopressin
B. TSH and prolactin
C. GnRH and somatosatin
D. GH and gonadotropins

Answer

To solve the question, "Which of the following pass through the hypothalamic neurons and not through the hypophyseal pituitary portal circulation?", we will follow these steps:

### Step 1: Understand the Role of the Hypothalamus
The hypothalamus is a crucial part of the endocrine system, acting as the master regulator. It produces various hormones that control the pituitary gland's function.

**Hint:** Remember that the hypothalamus connects directly to the pituitary gland and regulates its activity.

### Step 2: Differentiate Between the Anterior and Posterior Pituitary
The pituitary gland has two main parts: the anterior pituitary and the posterior pituitary. The anterior pituitary receives hormones through the hypophyseal portal circulation, while the posterior pituitary receives hormones directly from the hypothalamus.

**Hint:** Focus on how hormones reach each part of the pituitary gland.

### Step 3: Identify Hormones Released by the Posterior Pituitary
The posterior pituitary releases hormones that are synthesized in the hypothalamus. The two primary hormones released from the posterior pituitary are oxytocin and vasopressin (also known as antidiuretic hormone, ADH).

**Hint:** Recall which hormones are produced in the hypothalamus and stored in the posterior pituitary.

### Step 4: Analyze the Options
The question asks which hormones pass through the hypothalamic neurons and not through the hypophyseal portal circulation. Since oxytocin and vasopressin travel along the axons of hypothalamic neurons directly to the posterior pituitary, they do not enter the portal circulation.

**Hint:** Compare the pathways of different hormones to determine which ones bypass the portal system.

### Step 5: Conclusion
Based on the above analysis, the hormones that pass through the hypothalamic neurons and not through the hypophyseal pituitary portal circulation are oxytocin and vasopressin.

**Final Answer:** Oxytocin and vasopressin.