Fig. 1

EM images of brain microvessels. A Scanning electron micrograph of a replica of cortical capillaries in the frontal lobe of the human brain (from [74]). B Scanning electron micrograph of a replica of a cortical capillary network in the human brain showing the imprint of endothelial cell nuclei (2) and a pericyte with a “bump on a log” morphology (3) (from [74]). C Cross-section of a capillary in the frontoparietal cortex of a Wistar–Kyoto rat showing an endothelial cell wrapping around to form a tight junction with itself, along with associated pericytes and astrocyte end-feet (from [70]). D Transmission electron microscope cross-section of a cortical capillary in a rat. A systemically injected lanthanum compound penetrated the inter-endothelial space up to the tight junction (from [71]). E Freeze-fracture replicas of cerebral endothelial cell tight junctions. In capillary preparations, most P-face strands are occupied with particles (from [75])