<prompt> Protein filtration across cerebral capillaries is limited by-Fibrous tissueFoot process of astrocytesLow BPHigh CSF pressure  <response>: 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 cellsfoot processes of the astrocytes around the capillariesAlso rememberAreas outside the blood brain barrierPosterior pituitaryArea postremaOVLT Organum vasculosum of the lamina terminalisSubfornical organThese are collectively ka circumventricular organs. 