The detection of nucleic acids at the ultrastructural level has a long standing history. Histochemical methods such as the EDTA-regressive staining1 to detect RNPs or the osmium-amine staining2,11 to detect DNA were among the first techniques introduced to electron microscopy (EM) to localize nucleic acids in general. Indirect detection procedures using enzymatic digestion with DNases and RNases offered an alternative approach. Later on, methods derived from molecular biology were added to the repertoire of methods such as the terminal deoxynucleotidyl transferase reaction for 3′ end labeling of DNA14 or in situ nick translation for detection of DNA.13 Immune reactions using an anti-DNA antibody offer an easy-to-use alternative for labeling DNA in EM.15