pituitary gland [L, pituita, phlegm] , an endocrine gland suspended beneath the brain in the pituitary fossa of the sphenoid bone, supplying numerous hormones that govern many vital processes. It is divided into an anterior adenohypophysis and a smaller posterior neurohypophysis. The anterior lobe of the gland is composed of polygonal cells related to the production of seven hormones. The hormones, controlled by hypothalamic releasing factors, include growth hormone (somatotropin), prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and melanocyte-stimulating hormone. The posterior lobe is morphologically an extension of the hypothalamus and the source of vasopressin (antidiuretic hormone) and oxytocin. Vasopressin inhibits diuresis by promoting nephron water reabsorption and raises blood pressure. Oxytocin stimulates the contraction of smooth muscle, especially in the uterus. Also called hypophysis, hypophysis cerebri. See also adenohypophysis, neurohypophysis.
