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• The pituitary gland, also known as the hypophysis, is a small gland located in the sella turcica, a bony cavity at the base of the brain. It's separated from the cerebrospinal fluid by the arachnoid membrane, also known as the diaphragm sellae.
• The optic chiasm is situated 5-10 mm above this diaphragm.
• The pituitary gland is connected to the hypothalamus via the pituitary (hypophyseal) stalk.
• The pituitary stalk, also referred to as the infundibular stalk or the infundibulum, is the link between the hypothalamus and the pituitary gland. A suprasellar tumor compressing the pituitary stalk can decrease all anterior pituitary hormones except for prolactin, which increases, leading to prolactinoma.
• Physiologically, the pituitary gland is divided into two distinct parts:
  • The anterior pituitary, also known as adenohypophysis, originates from Rathke’s pouch, an embryonic invagination of the pharyngeal epithelium.
  • The posterior pituitary, also referred to as the neurohypophysis, originates from a neural tissue outgrowth from the hypothalamus.
• Anatomically, there is an intermediate lobe of the pituitary, which synthesizes and secretes the melanocyte-stimulating hormone (MSH).
• The anterior pituitary secretes six important peptide hormones and several less important ones, while the posterior pituitary secretes two important peptide hormones. The hormones of the anterior pituitary play major roles in controlling metabolic functions throughout the body.

Anterior pituitary hormones:

• Each major hormone formed in the anterior pituitary gland originates from a specific cell type. At least five cell types can be differentiated:

  1. Somatotropes: Produce human growth hormone (GH).
  2. Corticotropes: Produce adrenocorticotropic hormone (ACTH).
  3. Thyrotropes: Produce thyroid-stimulating hormone (TSH).
  4. Gonadotropes: Produce gonadotropic hormones, which include both luteinizing-hormone (LH) and follicle-stimulating hormone (FSH).
  5. Lactotropes: Produce prolactin (PRL).

• About 30 to 40 percent of the anterior pituitary cells are somatotropes acidophils that secrete growth hormone. Around 20 percent are corticotropes that secrete ACTH. Each of the other cell types accounts for only 3 to 5 percent of the total.

• The hypothalamus secretes many substances which influence the secretion of anterior pituitary by secreting releasing or inhibiting hormones. Some of these include:

1. Growth hormone releasing hormone (GHRH) is more present in children.
2. Growth hormone inhibitory hormone (GHIH) is more present in adults. It's also called somatostatin hormone.
3. Prolactin inhibitory hormone (PIH) inhibits prolactin secretion and is also called dopamine.
4. Thyrotropin releasing hormone (TRH).
5. Corticotropin releasing hormone (CRH).
6. Gonadotropin releasing hormone (GRH).