FIgure 1 (click to view)

The pituitary gland is a bean-shaped small organ, located in the sellar fossa, in the centre of the skull base at the base of the brain. The word “pituitaria” is derived from the Greek word “ptuo”, which means “spew” and the Latin word “ptuita” (mucus). The normal size of
the gland is approximately 10 mm in length, 5 to 10 mm in height and 10 to 15 mm in width (Figure 1 and Figure 2). The normal weight is 500-600 mg. This organ plays a central role in hormone regulation; it integrates hormonal signals that control adrenal, thyroid, reproductive, growth, and metabolic functions.

The pituitary gland is divided in the anterior and the posterior lobe, the so-called adeno- and neurohypophysis. The anterior lobe contains 75 percent of the pituitary gland, in which

Figure 2 (click to view)

different hormones are produced. The most important are: growth hormone (GH), prolactin (Pr), adrenocorticotrophic hormone (ACTH), thyrotropin (TSH), luteinising hormone (LH) and follicle-stimulating hormone (FSH), produced by at least 5 different cell-types. These different cell types are clustered and have their own position in the pituitary gland; ACTH and TSH in the centre of the anterior pituitary lobe and PR and GH at both lateral sides. The posterior lobe is a storage for anti-diuretic hormone (ADH) and oxytocin, produced in the hypothalamus. The pituitary gland has a connection with the hypothalamus via the pituitary stalk and portal system. Neighbouring structures are the optic chiasm and optic nerves antero-superior, the sphenoid sinus antero-inferior, the cavernous sinus and the cranial nerves III, IV, V and VI at both lateral sides and dorsal the clivus.