pituitary, posterior

pituitary, posterior The back portion of the pituitary gland. The posterior pituitary secretes the hormone oxytocin, which increases uterine contractions and antidiuretic hormone (ADH), which increases reabsorption of water by the tubules of the kidney. Underproduction of ADH results in diabetes insipidus, which is characterized by inability to concentrate the urine and, consequently, excess urination, leading potentially to dehydration. See also antidiuretic hormone; diabetes insipidus; oxytocin. Also known as neurohypophysis.