Fluorescamine, a fluorescence probe for amino groups in histochemical studies of plant cells and the effect of mercury fixation.

When fixed in mercuric chloride solutions and stained with Fluorescamine, histological plant specimens emit a strong fluorescence. The fluorophore distribution is topologically identical to the staining pattern revealed by visible light methods for nucleoproteins, but the fluorescence mode of viewing preparations gave greater sensitivity and contrast than transmitted light absorption methods. The parameters that influence the formation of the fluorescent image in plant cells are discussed. The results obtained indicate that the mercury-Fluorescamine reaction is an ideal histochemical procedure for collecting qualitative and analytical information on plant nuclei and on the changes of nucleolar architecture that occur during the cellular developmental cycle.