This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous Nervous System, Subject name: Physiology
Protein filtration across cerebral capillaries is limited by- 
Select and explain. 
A. Fibrous tissue, B. Foot process of astrocytes, C. Low BP, D. High CSF pressure
B: Foot process of astrocytes
Answer: B: Foot process of astrocytes 
Explanation: Ans. is 'b' is Foot process of astrocytes. Blood brain barrier does not allow filtration of any substances across it except for lipid soluble substances.It is formed by thetight junctions of the endothelial cells*foot processes of the astrocytes around the capillaries*Also rememberAreas outside the blood brain barrierPosterior pituitary*Area postrema*OVLT (Organum vasculosum of the lamina terminalis)*Subfornical organ*These are collectively k/a circumventricular organs*.