Figure 1.

Structure and biological transport mechanisms of the BBB

(A) The BBB is mainly composed of vascular endothelial cells surrounded by pericytes, basal lamina, a layer of astrocyte terminal protrusions, and microglia. These cells are involved in maintaining the integrity of the BBB.

(B) Representative pathways of CDVs crossing the BBB including receptor-mediated transcytosis, adsorptive-mediated transcytosis, transporter-mediated transcytosis, and paracellular pathway. ZO-1, zonula occludens-1, also known as tight junction protein-1; ZO-2, zonula occludens-2; JAM, junctional adhesion molecules.¹²