We report a novel fluorescence imaging approach to imaging nonfluorescence-labeled biological tissue samples. The method was demonstrated by imaging neurons in Golgi-Cox-stained and epoxy-resinembedded samples through the excitation of the background fluorescence of the specimens. The dark neurons stood out clearly against background fluorescence in the images, enabling the tracing of a single dendritic spine using both confocal and wide-field fluorescence microscopy. The results suggest that

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... e reported fluorescence imaging method would provide an effective alternative solution to image nonfluorescence-labeled samples, and it allows tracing the dendritic spine structure of neurons.