Abstract: A suspension of True Blue (TB) in physiological saline was injected into the posterior chamber of the eye in rats aged 7 days, 14 days, and 28 days. Animals were killed at 1, 3, 5, 7 or 9 days post injection. Axons and oligodendroglia were labeled. Fluorescence in the optic nerve was greatest near the orbit and declined toward the optic chiasm. During rapid myelination (14 days) and late myelination (28 days) period. fluorescence labeled glias were especially abundant. The labeled glia were characteristically arranged in rows running longitudinally throughout the optic nerve. Fluorescence in the glia increased from the fifth days after the injection of the dye. The evidence supports a hypothesis that the fluorescent dye entered the oligodendroglia directly by axonal transport mechanism, possibly at the paranodal, axo-glial junction.

Key words: fluorescent dye, optic nerve, axon, oligodendroglia, rat