Photomicrography of weakly fluorescent objects--employment of p-phenylene diamine as a blocker of fading.

By adding p-phenylene diamine (PPD) to the embedding medium, the fading of fluorescent objects labeled with FITC or mithramycin is substantially reduced. Thus, a multiple quantity of light, as compared to without additive, may be obtained from the objects and so photomicrography be improved or made possible at all. For microfluorometry as well as for subjective fluorescence microscopy the employment of PPD is not very helpful.