“…This appears to be mediated by fluid-phase endocytosis at the plasma membrane, rather than penetration through the lipid bilayer [39,66]. While tau aggregates are readily taken into cells, monomeric tau does not gain access to the intracellular space [39,66], implying higher-order oligomers may be required for efficient internalization. Microfluidic chambers have been used to show that tau aggregate uptake is possible at the somatodendritic compartment as well as axon terminals, and fibrils can be transported both anterograde and retrograde once inside neurons [66].…”