Circumventricular organs (CVOs) (circum-: around ; ventricular: of ventricle) are structures in the brain characterized by their extensive and highly permeable capillaries, unlike those in the rest of the brain where there exists a blood–brain barrier (BBB) at the capillary level. Although the term "circumventricular organs" was originally proposed in 1958 by Austrian anatomist Helmut O. Hofer concerning structures around the brain ventricular system, the penetration of blood-borne dyes into small specific CVO regions was discovered in the early 20th century. The permeable CVOs enabling rapid neurohumoral exchange include the subfornical organ (SFO), the area postrema (AP), the vascular organ of lamina terminalis (VOLT — also known as the organum vasculosum of the lamina terminalis (OVLT)), the median eminence, the pituitary neural lobe, and the pineal gland.
The circumventricular organs are midline structures around the third and fourth ventricles that are in contact with blood and cerebrospinal fluid, and they facilitate special types of communication between the central nervous system and peripheral blood. Additionally, they are an integral part of neuroendocrine function. Highly permeable capillaries allow the CVOs to act as an alternative route for peptides and hormones in the neural tissue to sample from and secrete to circulating blood. CVOs also have roles in body fluid regulation, cardiovascular functions, immune responses, thirst, feeding behavior and reproductive behavior.
CVOs can be classified as either sensory or secretory organs serving homeostatic functions and body water balance. The sensory organs include the area postrema, the subfornical organ, and the vascular organ of lamina terminalis, all having the ability to sense signals in blood, then pass that information neurally to other brain regions. Through their neural circuitry, they provide direct information to the autonomic nervous system from the systemic circulation. The secretory organs include the subcommissural organ (SCO), the pituitary gland, the median eminence, and the pineal gland.
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Covers the development of the central nervous system and the secretion of growth hormone, along with the treatment of acromegaly using somatostatin analogs.
The area postrema, a paired structure in the medulla oblongata of the brainstem, is a circumventricular organ having permeable capillaries and sensory neurons that enable its dual role to detect circulating chemical messengers in the blood and transduce them into neural signals and networks. Its position adjacent to the bilateral nuclei of the solitary tract and role as a sensory transducer allow it to integrate blood-to-brain autonomic functions.
The median eminence is generally defined as the portion of the ventral hypothalamus from which the portal vessels arise. The median eminence is a small swelling on the tuber cinereum, posterior to and atop the pituitary stalk; it lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region by the optic chiasm. As one of the seven areas of the brain devoid of a blood–brain barrier, the median eminence is a circumventricular organ having permeable capillaries.
The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside. The blood–brain barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane.
Neurons primarily communicate through release of neurotransmitter from presynaptic specialisations along their axonal arborisations. In order to understand the functional role of a specific neuron, it is therefore of great interest to know the structure of ...
The pathogenic bacterium Streptococcus pneumoniae (S. pneumoniae) can invade the cerebrospinal fluid (CSF) and cause meningitis with devastating consequences. Whether and how sensory cells in the central nervous system (CNS) become activated during bacteri ...
Spinal muscular atrophy (SMA) is a neuromuscular disease caused by loss of the SMN1 gene and low SMN protein levels. Although lower motor neurons are a primary target, there is evidence that peripheral organ defects contribute to SMA. Current SMA gene ther ...