The posterior pituitary gland, or neurohypophysis, contains nerve endings from the hypothalamus that secrete two hormones: antidiuretic hormone (ADH or vasopressin) and oxytocin. These hormones are synthesized in the hypothalamus and transported to the posterior pituitary. ADH regulates water balance by increasing water permeability in the kidneys. Oxytocin causes uterine contraction during childbirth and milk ejection from the breasts during lactation. Both hormones are regulated by osmolarity and blood volume/pressure.