This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
"Blood brain barrier" is present at all of the following sites except 
Select and explain. 
A. Habenular nucleus, B. Subfornical organ, C. Cerebellum, D. Pontine nucleus
B: Subfornical organ
Answer: B: Subfornical organ 
Explanation: Structures outside blood brain barrier
-        Posterior pituitary
-        Ventral part of median eminence of hypothalamus
-        Area postrema
-        Organ vasculosum of lamina terminalis (OVLT)
 
-        Subfornical organ