Lucifer yellow – an angel rather than the devil

Abstract Introduction A very brief history of intracellular labelling techniques Methods for loading cells with LY Electrophysiological studies using LY‐filled electrodes Studying cell morphology with LY Using LY to study intercellular communication Retrograde labelling with LY Photoconversion of LY Combination of LY labelling with other methods Antibodies against LY Using LY for selective ablation of cells Conclusion The fluorescent dye Lucifer yellow (LY) was introduced in 1978, and has been extremely useful in studying cell structure and communications. This dye has been used mostly for labelling cells by intracellular injection from microelectrodes. This review describes the numerous applications of LY, with emphasis on the enteric nervous system and interstitial cells of Cajal. Of particular importance is the dye coupling method, which enables the detection of cell coupling by gap junctions.