Bidirectional fluorescent labelling techniques for the developing and regenerating visual system

Fluorescent dyes like RITC or Dil (282) are convenient and highly efficient labelling substances for investigating developing and regenerating neurons. Either dye can be taken up by cell bodies and transported in an anterograde direction, resulting in a complete outlining of the axons and their growth cones. Additionally the dyes can be transported in a retrograde direction, resulting in labelling on the cell bodies and their dendrites. These dyes have several features in common, for instance their poor solubility in aqueous buffers, the absence of neurotoxicity and the long time persistence in the filled neurons. Dil can in particular be used for the staining of neurons post-mortem. These dyes have also been used to address several questions concerning fiber growth and pathfinding during embryogenesis of the visual system, and during the period of axonal regeneration of adult retinofugal fibers.