What gland secretes adrenocorticotropin hormone?

The pituitary gland is responsible for secreting adrenocorticotropic hormone (ACTH). This hormone plays an essential role in stimulating the adrenal glands to produce cortisol, which helps regulate metabolism, immune response, and stress reactions. ACTH is a key component of the hypothalamic-pituitary-adrenal (HPA) axis, which is crucial for maintaining homeostasis in response to stressors. The release of ACTH is controlled by corticotropin-releasing hormone (CRH) produced by the hypothalamus.

In the context of the other glands mentioned, the thyroid gland primarily produces thyroid hormones such as thyroxine (T4) and triiodothyronine (T3), which are involved in regulating metabolism. The adrenal gland is involved in hormone production but responds to ACTH rather than secreting it, while the pancreas is responsible for insulin and glucagon secretion related to glucose metabolism. Thus, the pituitary gland is the correct answer as it is the origin of ACTH synthesis and release.