The dynamic transportation of exogenous Aβ in the retina through the brain – eye drainage route. (A) Short and long-term observation timelines of fluorescently labeled human Aβ injected into the CM. (B) Confocal images showing the transportation of Aβ in the retina, optic nerve, and its sheath after 30 min. (C and D) Immunofluorescence staining and 3D reconstructed images of the optic nerve revealed that Aβ travels along the PVS adjacent to the CRA, which was co-labeled with αSMA (green) and Laminin (blue). Arrowheads indicated the path of Aβ transport. (E–G) Immunostaining and statistical graphs demonstrated Aβ signals in arteries and veins of retina and optic nerve 10 and 30 min after CM injection (n = 6). Areas with αSMA⁺ Laminin⁺ staining were labeled as “A” for arteries, and areas with αSMA⁻ Laminin⁺ staining were labeled as “V” for veins. (H and I) Representative images of Aβ tracer signal 30 min after injection in the lymphatic vessels adjacent to the optic nerve, characterized by LYVE1⁺ Laminin⁻ staining, as well as in the gaps between myelinated axons within the optic nerve, marked by MBP and TUJ1.