The pituitary gland is located in a bony cavity called sella tursica and is attached to hypothalamus by a stalk. It is divided anatomically into an adenohypophysis and a neurohypophysis. The latter is also called pars nervosa or posterior pituitary. It stores and releases two hormone called oxytocin and vasopressin, which are actually synthesized by the hypothalamus and are transported axonally to neurohypophysis. Vasopressin acts mainly at the kidney and stimulates resorption of water and electrolytes by the distal tubules in the nephron and therby reduces loss of water through urine (divereses). Hence, it is also called as anti-diuretic hormone (ADH) .