Fig. 2.

The blood–brain barrier. Schematic representation (a) and electron microscopic image (b) of tight and adherens junctions found in brain endothelium. b High-magnification electron microscopic image showing a tight junction (arrowheads) in a brain capillary of an adult mouse. Scale bar 200 nm. c Schematic representation of the cellular and molecular mechanisms regulating transcellular permeability of the blood–brain barrier. EC endothelial cell, Aa amino acids, Glc glucose, XB xenobiotics, MAO monoamine oxidase, GGT gamma-glutamyl transpeptidase, LDL low-density lipoprotein