M02.01.06 The pituitary gland

The pituitary gland, also known as the hypophysis, is a small endocrine gland located at the base of the brain, just below the hypothalamus. It plays a vital role in regulating various hormonal functions in the body. Here’s a detailed anatomy of the pituitary gland:

1. Anatomy:
   • Size and Shape: The pituitary gland is approximately 1 centimeter in diameter and has a rounded shape.
   • Location: It is situated within the sella turcica, a bony cavity in the sphenoid bone at the base of the skull.
   • Divisions: The pituitary gland is divided into two main parts: the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis).
2. Histology:
   • Anterior Pituitary: The anterior pituitary is composed of different cell types, including acidophils (secrete growth hormone and prolactin), basophils (secrete the adrenocorticotropic hormone, thyroid-stimulating hormone, and follicle-stimulating hormone), and chromophobes (non-staining cells with unknown function).
   • Posterior Pituitary: The posterior pituitary consists mainly of nerve fibers and glial-like cells called pituicytes, which provide structural support.

Blood Supply:

• Superior Hypophyseal Arteries: Arise from the internal carotid arteries and supply the median eminence, the infundibulum, and the anterior pituitary.
• Inferior Hypophyseal Arteries: Branch from the internal carotid or the posterior communicating arteries and supply the posterior pituitary.
• Hypophyseal Portal System: A network of blood vessels connects the hypothalamus with the anterior pituitary, allowing the transport of releasing and inhibiting hormones from the hypothalamus to the pituitary.
• 

Clinical Relevance:

1. Pituitary Adenomas: Pituitary adenomas are the most common pituitary tumors. They can be functional, producing excess hormones, or non-functional, causing hormonal deficiencies due to compression of surrounding structures. Symptoms depend on the hormones affected and can include hormonal imbalances, visual disturbances, headaches, and neurological deficits.
2. Pituitary Dysfunction: Dysfunction of the pituitary gland can lead to various endocrine disorders, including growth hormone deficiency, Cushing’s disease (excess cortisol), hyperprolactinemia (excess prolactin), and hypopituitarism (deficient hormone production).
3. Diabetes Insipidus: Damage or dysfunction of the posterior pituitary can result in diabetes insipidus, a condition characterized by excessive thirst and increased urine output due to insufficient production or release of antidiuretic hormone (ADH).
4. Pituitary Apoplexy: Pituitary apoplexy is a rare but potentially life-threatening condition characterized by sudden bleeding or hemorrhage into the pituitary gland, usually in the setting of a pituitary adenoma. It can present with severe headaches, visual disturbances, hormonal imbalances, and neurological symptoms.
5. Pituitary Surgery: Surgical intervention, such as transsphenoidal surgery, is often performed to remove pituitary tumors or manage certain pituitary disorders. The goal is to relieve pressure on surrounding structures, restore hormone balance, and alleviate symptoms.

Understanding the anatomy, histology, blood supply, and clinical relevance of the pituitary gland is crucial in diagnosing and managing pituitary disorders. Various imaging techniques, such as MRI, are used to visualize the pituitary gland and detect abnormalities. Hormonal tests, visual field assessments, and neurological evaluations are also employed to assess pituitary function and diagnose related conditions.