hypofys

Hypophysis, or the pituitary gland, is a small endocrine organ located at the base of the brain within the sella turcica. It sits in close relation to the hypothalamus and is connected to it by the infundibulum. The gland plays a central role in coordinating growth, metabolism, reproduction, and water balance.

The pituitary has two distinct parts: the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis). The anterior pituitary develops from Rathke's pouch, an outpouching of oral ectoderm, whereas the posterior pituitary derives from neural tissue. The two lobes have different cellular compositions and regulatory mechanisms.

The anterior pituitary secretes six major hormones: thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), growth hormone (GH), and prolactin. The posterior pituitary stores and releases vasopressin (antidiuretic hormone, ADH) and oxytocin, which are synthesized in hypothalamic neurons and transported down neurosecretory fibers to the posterior lobe.

Regulation involves hypothalamic control: releasing and inhibiting hormones reach the anterior pituitary via the hypophyseal portal system, whereas the posterior pituitary is regulated by direct neural connections from the hypothalamus. Hormone production is subject to negative feedback from target organs, creating integrated endocrine axes such as the hypothalamic-pituitary-thyroid, -adrenal, and -gonadal systems, as well as lactation control.

Clinically, the pituitary is a common site for tumors, most often benign adenomas, which can cause hormone excess or deficiency. Prolactinomas, GH-secreting adenomas (acromegaly or gigantism), and ACTH-secreting adenomas (Cushing disease) are notable examples. Pituitary dysfunction can lead to diabetes insipidus or hypopituitarism, with diverse systemic effects.