The Endothelium of the Brain Microvasculature and the Organization of Intercellular Junctions

Abstract

The endothelium is considered to be a sparse organ system due to its vast extension and its ability to exert a complex array of specialized functions [1, 2]. A unique characteristic of endothelial cells (EC) is that, although they present many common functional and morphological features, they also display remarkable heterogeneity in different organs. Here, we will focus on the endothelium of the brain microvasculature, which represents the interface between blood and the central nervous system. We will also examine how its functional properties may be mediated by intercellular junctions. Due to its unique location, the microvascular endothelium of the brain has specific protective properties which strictly regulate the infiltration of plasma components and circulating cells into the brain. The blood-brain barrier normally permits the passage of only small hydrophobic molecules, a limited number of specifically transported nutrients such as glucose and amino acids, and some transcytosed molecules such as transferrin (reviewed in [3–5]).