Fluorescent latex microspheres as a retrograde tracer in the peripheral nervous system

Rhodamine labeled latex microspheres were used as a fluorescent retrograde tracer in the peripheral nervous system. Examination of rabbit trigeminal ganglia following application of microspheres to crushed or intact inferior alveolar nerve revealed that: (1) microspheres were taken up by only damaged axons; (2) microspheres remained in trigeminal cell bodies for up to 3 months without degradation or diffusion to extracellular structures; and (3) cells containing microspheres were capable of regenerating axons as evidenced by the return of evoked sensory action potentials and the retrograde axonal transport of True blue. Thus, fluorescent microspheres may be useful tools for in vivo survival studies of peripheral nervous system regeneration and development.