Morphofunctional Organization of the Subfornical Organ

This review contains literature data covering the structure and functions of the subfornical organ (SFO). The SFO belongs to the sensory group of formations located around the III and IV ventricles and constituting the circumventricular system of the brain. Despite its small size, the SFO has four departments, which differ from each other in the features of cyto-, myelo-, and angioarchitectonics. The structural features of the blood-brain barrier in the SFO allow many substances to directly contact with its cellular elements. A distinctive feature of the SFO is that circulating substances can stay in the capillaries for an unusually long time. Perivascular spaces, located around type I and III capillaries, penetrate the organ like thin channels and provide the substances in the interstitial fluid with a large surface area for interacting with the receptor field. A characteristic feature of the SFO is tanycytes, whose intertwining processes extend throughout the organ and form multiple contacts with neurons and the vascular bed. SFO is an important link in the regulation of homeostasis. It takes part in the regulation of blood pressure and drinking behavior, controls the water and electrolyte balance and energy metabolism, and also acts as an important link in neuro-immune interactions. Such structural and functional features of the SFO make it a promising object of neurobiological research.