circumventricular organ
Also written as: CVO — Circumventricular Organ
Specialized brain regions lacking a complete blood-brain barrier that allow direct communication between the central nervous system and peripheral circulation.
Full Definition
Circumventricular organs (CVOs) are seven specialized brain structures characterized by increased vascular permeability due to fenestrated capillaries and absence of tight junctions typical of the blood-brain barrier. These include the posterior pituitary, median eminence, organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), area postrema, subcommissural organ, and pineal gland. CVOs serve as critical interfaces for neuroendocrine regulation, allowing neurons to sense blood-borne signals like hormones, nutrients, and toxins, and to release neurohormones directly into circulation. They play essential roles in homeostatic regulation including fluid balance, feeding, and circadian rhythms.
Usage
Usage note: Commonly abbreviated as CVO; ensure proper identification of specific CVOs when relevant to clinical context.
In Context
- "The subfornical organ and other circumventricular organs detected the elevated angiotensin II levels." — Physiology textbook
- "Damage to circumventricular organs may explain the patient's impaired osmotic sensing." — Clinical case discussion