Circumventricular Organs: Area Postrema, Median Eminence and Neurohypophysis, Subcommissural Organ, Pineal Gland and Choroid Plexus

There are seven circumventricular organs in the rat brain, which have been given this classification because they are all located in the walls of the lateral, third, or fourth ventricles of the brain. The subfornical organ, the vascular organ of the lamina terminalis (OVLT), the pineal gland, the subcommissural organ, and the median eminence/neurohypophyseal complex are located in different places in the wall of the third ventricle. The area postrema is located in the wall of the fourth ventricle. The choroid plexus can be found in the lumen of the lateral, third, or fourth ventricle.