The design of barriers in the hypothalamus allows the median eminence and the arcuate nucleus to enjoy private milieus: the former opens to the portal blood and the …

EM Rodríguez, JL Blázquez, M Guerra - Peptides, 2010 - Elsevier
The blood-brain barrier (BBB) is a single uninterrupted barrier that in the brain capillaries is
located at the endothelial cells and in the circumventricular organs, such as the choroid
plexuses (CP) and median eminence (ME), is displaced to specialized ependymal cells.
How do hypothalamic hormones reach the portal circulation without making the BBB leaky?
The ME milieu is open to the portal vessels, while it is closed to the cerebrospinal fluid (CSF)
and to the arcuate nucleus. The cell body and most of the axons of neurons projecting to the …