Fig. 1

Perivascular glymphatic transport in the brain. Schematic depicting the proposed mechanism underlying molecular transport in brain tissue, the glymphatic system. Perivascular spaces (PVS) surround cerebral blood vessels and are bounded by the vascular wall on the inside and by the ‘endfeet’ of astrocyte cells (green) on the outside. It is proposed that cerebrospinal fluid moves inward from the subarachnoid space along periarterial spaces surrounding penetrating arteries deep into the brain. The fluid enters the interstitium through gaps between astroglial endfeet. Interstitial solutes (‘waste’) are cleared by interstitial convection towards peri-venous spaces and extracranial efflux routes. Perivascular CSF influx and interstitial solute efflux is facilitated by astroglial aquaporin-4 (AQP4) water channels. Reproduced from [13] with nomenclature updated from ‘para-arterial’ to ‘periarterial’