Anatomy, Adenohypophysis (Pars Anterior, Anterior Pituitary)

One of the unique glands in the human body is the pituitary gland. The gland is oval and weighs 500 mg. The dimension of the pituitary gland is about 12 mm transverse and 8 mm in anterior-posterior diameter. The pituitary is located in the hypophysial fossa, in a bony depression of the sphenoid bone called the sella turcica. The sella turcica surrounds the gland's inferior, anterior, and posterior aspects. Various structures surround the endocrine gland. The optic chiasma lies anteriorly, and the mammillary bodies lie posteriorly. Superior to the pituitary gland is the diaphragma sellae, the sphenoidal air sinuses are inferior, and the cavernous sinuses are lateral. A fold of dura matter covers the pituitary and has an opening to allow for the infundibulum to pass through, allowing a connection to the hypothalamus. The gland consists of 2 lobes: 1. Adenohypophysis (see  Anatomy, Adenohypophysis). 2. Neurohypophysis. This topic focuses on the adenohypophysis. The anterior pituitary is composed of the following parts: Pars distalis: This is the portion where most hormone production occurs. It is the distal part of the pituitary and forms the majority of the adenohypophysis. Pars tuberalis: this tubular sheath extends from the pars distalis and winds around the pituitary stalk. Epithelial cells arranged in cords and hypophyseal portal vessels reside in this space. Pars intermedia: This is a tissue section between the posterior pituitary and pars distalis. This section of the adenohypophysis consists of large pale cells. These cells of the pars intermedia encompass follicles containing a colloidal matrix. The main hormone secreted by this portion of the adenohypophysis is MSH, otherwise known as the melanocyte-stimulating hormone.