The single-cell gel electrophoresis or comet assay was initially reported in 1984 as a novel technique to directly visualize DNA damage in individual cells (1 ). The method was modified by adding strong alkaline conditions to denature genomic DNA and detect alkali labile lesions, greatly improving sensitivity for single-strand breaks (2 ,3 ). This simple assay has come into widespread use because of its sensitivity, need for few cells, applicability to nearly all eukaryotic cells, and ease in processing numerous samples (4 ).
