Some areas of the brain lack blood-brain barrier. These are called the circumventricular organs because they surround the ventricular system in the brain. They are supplied by leaky capillaries. These areas are: Area postrema (CTZ is located in this area) Posterior pituitary Subfornical organ (SFO) (a specialized receptor area in diencephalon; angiotensin II acts on it to stimulate thirst) Median eminence (poion of the hypothalamus from which the poal vessels arise) Pineal gland Organum vasculosum laminae terminalis (OVLT) (function similar to SFO)