PITUITARY GLAND

Pituitary gland


[NA]. An unpaired compound gland suspended from the base of the hypothalamus by a short extension of the infundibulum, the infundibular or pituitary stalk. The hypophysis consists of two major subdivisions: 1) the neurohypophysis, comprising the infundibulum and its bulbous termination, the neural part or infundibular process (posterior lobe), which is composed of neuroglia-like pituicytes, blood vessels, and unmyelinated nerve fibers of the hypothalamohypophyseal tract whose cell bodies reside in the supraoptic and paraventricular nuclei of the hypothalamus, and convey to the lobe for storage and release the neurosecretory hormones oxytocin and antidiuretic hormone; 2) the adenohypophysis, comprising the larger distal part, a sleeve-like extension of this lobe (infundibular part) which invests the infundibular stalk, and a thin intermediate part (poorly developed in humans) between the anterior and posterior lobes; the anterior lobe consists of cords of cells of several different types interspersed with capillaries of the hypothalamohypophysial portal system; secretion of somatotropins, prolactin, thyroid-stimulating hormone, gonadotropins, adrenal corticotropin, and other related peptides in the adenohypophysis is regulated by