Table 1.

Short overview of the characteristics of the circumventricular organs

	Type	Location	Size [mm]	Primary function	Hormones	Ref.
NH	Secretory	Posterior part of the hypophysis originating from the floor of the third ventricle	1.0–2.9	Releasing hormones received from the paraventricular and supraoptic nuclei	Vasopressin Oxytocin	[2, 23]
ME	Secretory	Extension of the floor of the third ventricle	0.3	Hypophysial portal system: transporting hormones to the hypophysis	Vasopressin Oxytocin	[2, 24]
PG	Secretory	Posterior wall of the third ventricle	1.7	Regulating circadian rhythms	Melatonin	[2, 6]
OVLT	Sensory	Rostral wall of the third ventricle	0.2	Water and sodium homeostasis and immune response	Angiotensin II Cytokines	[2, 4, 6]
SFO	Sensory	Inferior surface of the fornix/roof of the third ventricle	0.3–0.6	Water and sodium homeostasis	Angiotensin II	[2, 6]
AP	Sensory	Floor of the fourth ventricle	0.5	Opening the central canal, cardiovascular and respiratory regulation and controlling the vomiting center	Substance P	[2, 4, 6]

NH neurohypophysis, ME median eminence, PG pineal gland, SFO subfornical organ, OVLT organum vasculosum of the lamina terminalis, AP area postrema