Fluorescent neuroanatomic techniques,. such as immunofluorescence and
retrograde and anterograde tracing studies, derive great utility from
their specificity. However, the specificity can be a drawback as well,
in that it may be difficult to assess labeled neurons or neural proce
sses in their cytoarchitectonic context. We report the characteristics
of a newly synthesized fluorescent counterstain, Fluoro Nissl Green (
3,8-diamino-10H-quindoline) with spectral characteristics similar to f
luorescein. This Nissl-like counterstain can be used as a green neuron
al counterstain for red-emitting markers such as rhodamine and Di-I.