Supplementary materials for "Cerebrospinal fluid flow extends to peripheral nerves further unifying the nervous system" include figures S1 to S16. These figures provide supporting data for the study. Figure S1 shows that low volume, high concentration nanoprobe injections yield similar deposition patterns as standard injections. Nanoprobe distribution recapitulates known CSF flow routes in the CNS, validating the CSF tracing system. Figure S3 shows that 1x PBS control tissues are unstained compared to nanoprobe-infused animals. Figure S4 shows control 1x PBS histological sections following gold enhance staining, showing clear meninges compared to nanoprobe-infused animals. Figure S5 shows gold enhance staining patterns of trigeminal nerves following five minute enhancement, showing that higher concentration of nanoprobe leads to more staining. Figure S6 shows average nanogold staining of peripheral nervous tissue after 0, 2, 4 and 6 hours, showing that staining increases over time. Figure S7 shows that CSF flows through spinal nerves in a time and distance dependent manner. Figure S8 shows quantification of dorsal versus ventral spinal nerve root staining. Figure S9 shows that perineurial cells contain lower levels of nanogold equivalent to CNS levels of staining. Figure S10 shows that nanogold accumulates on collagen fibers in the PNS. Figure S11 shows electron microscopy of central nervous system tissue, showing nanogold in the endoneurium. Figure S12 shows that unmyelinated Schwann cells exhibit low levels of intracellular nanogold. Figure S13 shows that nanogold is phagocytosed in peripheral nerves. Figure S14 shows that nanogold accumulates in extracellular and intracellular vesicles. Figure S15 shows electron microscopy of trigeminal nerves from control animals, showing no nanogold labeling. Figure S16 shows light microscopy of the nerves used for electron microscopy, showing high concentration of nanogold on the PNS side of the transition zone.Supplementary materials for "Cerebrospinal fluid flow extends to peripheral nerves further unifying the nervous system" include figures S1 to S16. These figures provide supporting data for the study. Figure S1 shows that low volume, high concentration nanoprobe injections yield similar deposition patterns as standard injections. Nanoprobe distribution recapitulates known CSF flow routes in the CNS, validating the CSF tracing system. Figure S3 shows that 1x PBS control tissues are unstained compared to nanoprobe-infused animals. Figure S4 shows control 1x PBS histological sections following gold enhance staining, showing clear meninges compared to nanoprobe-infused animals. Figure S5 shows gold enhance staining patterns of trigeminal nerves following five minute enhancement, showing that higher concentration of nanoprobe leads to more staining. Figure S6 shows average nanogold staining of peripheral nervous tissue after 0, 2, 4 and 6 hours, showing that staining increases over time. Figure S7 shows that CSF flows through spinal nerves in a time and distance dependent manner. Figure S8 shows quantification of dorsal versus ventral spinal nerve root staining. Figure S9 shows that perineurial cells contain lower levels of nanogold equivalent to CNS levels of staining. Figure S10 shows that nanogold accumulates on collagen fibers in the PNS. Figure S11 shows electron microscopy of central nervous system tissue, showing nanogold in the endoneurium. Figure S12 shows that unmyelinated Schwann cells exhibit low levels of intracellular nanogold. Figure S13 shows that nanogold is phagocytosed in peripheral nerves. Figure S14 shows that nanogold accumulates in extracellular and intracellular vesicles. Figure S15 shows electron microscopy of trigeminal nerves from control animals, showing no nanogold labeling. Figure S16 shows light microscopy of the nerves used for electron microscopy, showing high concentration of nanogold on the PNS side of the transition zone.