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Pituitary gland is a small endocrine gland located at the base of the brain under the optic chiasm and the arachnoid membrane, in a bony indentation called the sella turcica. Its name comes from the Greek hypophysis, which means undergrowth. The role of the pituitary gland is the regulated synthesis and secretion of polypeptide hormones that are essential for the development and function of many other organs in the body. Releasing hormones and inhibiting factors reach the anterior pituitary via hypothalamic neurons that terminate in the capillary beds of the median eminence, just dorsal to the pituitary gland. These capillary beds are connected to the hypophyseal portal vessels that nourish the anterior pituitary. In response to these stimulatory stimulatory factors, pituitary hormones are released into hypophyseal portal blood vessels and carried through the blood stream to their target organs. An intriguing feature of pituitary development is the initial organization of the cell types into discrete patches and the loss of this spatial organization as the organ expands. The rodent pituitary is composed of three lobes. The posterior pituitary (neurohypophysis or pars nervosa) is derived from neural ectoderm and contains the nerve terminals that secrete oxytocin and vasopressin. The intermediate lobe (pars intermedia) and anterior lobe are both derived from oral ectoderm. The bulk of the anterior lobe (pars distaIis) is at the same level as the intermediate lobe, but a portion of it known as the pars tuberalis extends dorsally along the pituitary stalk.