<unk>  of a mouse. In this photomicrograph, the<unk>  (arrow) is located on the undersurface of the fornix in the upper part of the third ventricle. The cells in this coronal section of the brain were colored with a bluish dye ("Nissl stain"). The thalamus is at the bottom of the photo. The bar at the lower right represents a distance of 200 μm (0.2mm). As noted above, capillaries in some subregions within the<unk>  are fenestrated, and thus lack a blood-brain barrier. All circumventricular<unk> s except the subcommissural<unk>  contain fenestrated capillaries, a feature that distinguishes them from most other parts of the brain. The<unk>  can be divided into six anatomical zones based on its capillary topography: two zones in the coronal plane and four zones in the sagittal plane. The central zone is composed of the glial cells, neuronal cell bodies and a high density of fenestrated capillaries. Conversely, the rostral and caudal areas have a lower density of capillaries and are mostly made of nerve fibers, with fewer neurons and glial cells seen in this area. Functionally, however, the<unk>  may be viewed in two portions, the dorsolateral peripheral division, and the ventromedial core segment. The<unk>  contains endothelin receptors mediating vasoconstriction and high rates of glucose metabolism mediated by calcium channels.
Subfornical organ
Stellate ganglion
Meibomian gland
Olfactory trigone
Syrinx 
Medulla 
Medulla
Aorticorenal ganglion