Abstract
Abstract: :
Purpose:To analyze the axon-tracing properties of indocyanine green (ICG). Methods:ICG was instilled in the vitreous or in the superior colliculus of rabbits and rats. Infrared fluorescence in the retina and the brain was subsequently revealed using a standard fundus camera with ICG filters. Results:After being introduced into the vitreous, ICG fluorescence was observed along the visual pathway up to the geniculate body and colliculus without detectable extracellular leakage. The fluorescence persisted at least 2 months. After instillation into the superior colliculus, retinal ganglion cell fluorescence was observed in the fundus of the awake rat. The axonal speed of ICG was estimated between 2 and 4 mm/hour. Conclusion:ICG is a convenient bidirectional fast axonal tracer, allowing to observe in the awake rat retrogradely labelled retinal ganglion cells with a standard fundus ICG camera.
Keywords: 474 microscopy: light/fluorescence/immunohistochemistry • 557 retina: proximal(bipolar, amacrine, and ganglion cells) • 593 superior colliculus/optic tectum