Macroscopic waste clearance system that utilizes a unique system of perivascular tunnels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system. [ https://github.com/obophenotype/uberon/issues/1260 http://dx.doi.org/10.1007/s11064-015-1581-6 http://www.informatics.jax.org/accession/sbello ]