Answer
The cicumventricular organs (CVO) are structure in the walls of the third and fourth ventricle; they include parts of the hypothalamus, pituitary,and pineal. The lack of BBB in CVOs facilitates the direct sampling of blood and enables them to coordinate neural and endocrine regulation of blood pressure, fluid balance, hunger and thirst.
Work Step by Step
The blood has direct to the brain at the CVOs. Unfortunately, this also permits access to the brain of HIV and other viruses at thees points.
