NETTER - Neuroscience Flash Cards

Circumventricular Organs
1. Subfornical organ
2. Pineal gland
3. Area postrema
4. Posterior pituitary gland
5. Median eminence
6. Organum vasculosum of the lamina terminalis (OVLT)
Comment: Circumventricular organs are known as “windows on
the brain” that are devoid of a blood-brain barrier with the usual
tight-junction endothelial appositions. The circumventricular organs
have vasculature with fenestrated capillaries. Some circumventricular
organs, such as the OVLT and area postrema, have neurons that
project to the hypothalamus and other visceral structures. They
also can release small molecule mediators such as prostaglandin
E2 (PGE2), thus affecting target structures at a distance. The
neurohypophysis is a site of release of oxytocin and vasopressin into
the general circulation. The median eminence is the site of release of
inhibitory factors and releasing factors for anterior pituitary hormones
into the hypophysial portal system. The pineal gland is the site of
synthesis and release of the hormone melatonin, influenced by
postganglionic noradrenergic sympathetic input.
Systemic Neuroscience See book 16.14