The same year, my review highlighted observations that mature mammalian ependymal cells possess the structural and enzymatic characteristics necessary for scavenging and detoxifying a wide variety of substances in the CSF, and the potential of forming a metabolic barrier at the brain–CSF interface. The presence of motile cilia, microvilli, and zonula adherens junctions at the apical surfaces is of importance for these roles. The presence of gap junctions was viewed as a potential means for coordinating the cell activity [45].