The pituitary gland is attached by a thin stalk to the under-surface of the?

The pituitary gland is indeed attached by a thin stalk, known as the infundibulum, to the under-surface of the brain. Specifically, it connects to the hypothalamus, which is a crucial area of the brain that plays a significant role in hormone regulation and various physiological functions. This anatomical relationship is vital because the hypothalamus sends signals to the pituitary gland to stimulate or inhibit hormone production, thereby regulating numerous bodily functions including growth, metabolism, and stress response.

The other options do not have a direct anatomical connection to the pituitary gland. The thyroid, ovaries, and pancreas are all important endocrine glands in different networks of hormone systems, but they are not structurally connected to the pituitary gland. Understanding this relationship helps clarify the role of the pituitary gland as the 'master gland' of the endocrine system, coordinating the activities of other glands through hormone signaling.