**Question:** All are seen in norma basalis except

A. Prolactin
B. Thyrotropin
C. Adrenocorticotropic hormone (ACTH)
D. Thyrotropin

**Core Concept:** Norma basalis is a region in the hypothalamus, located at the base of the third ventricle. It contains specific cells called neurosecretory cells, which produce and release various pituitary releasing hormones (e.g., gonadotropin-releasing hormone, thyrotropin-releasing hormone, and oxytocin). These hormones act on the anterior pituitary to stimulate the production and secretion of their respective hormones.

**Why the Correct Answer is Right:** The correct answer (D) is adrenocorticotropic hormone (ACTH) because ACTH is not produced by the norma basalis. ACTH is synthesized and secreted by the corticotrophs in the anterior pituitary, not in the norma basalis. It stimulates the adrenal cortex to produce cortisol, aldosterone, and other steroid hormones.

**Why Each Wrong Option is Incorrect:**

A. Prolactin (Option A) is also not produced by norma basalis. Prolactin is synthesized and released by lactotrophs in the anterior pituitary gland, which is responsible for milk production in females during pregnancy and lactation.

B. Thyrotropin (Option B) is produced by thyrotropes in the anterior pituitary, not in norma basalis. Thyrotropin stimulates the thyroid gland to produce thyroxine and triiodothyronine, which are involved in regulating the body's basal rate of cellular activity and energy production.

C. Adrenocorticotropic hormone (Option C, correct answer) is produced and released by corticotrophs in the anterior pituitary, not in norma basalis. ACTH plays a crucial role in regulating the adrenal cortex and cortisol production, which is essential for stress responses, immune system modulation, and glucose homeostasis.

**Clinical Pearl:** Understanding the anatomy and physiology of the hypothalamus-pituitary-adrenal axis is crucial for understanding the regulation of the body's stress response and maintaining hormonal balance. Any disruption in this axis can lead to several endocrine disorders, such as Cushing's syndrome (excess cortisol) and Addison's disease (deficiency of cortisol).