A comet assay, also known as a single cell gel electrophoresis assay, is a detection method to detect DNA damage in a eukaryotic cell. The cells are embedded in agarose on a microscope slide and then lysed to form nucleoids of supercoiled DNA. The gel electrophoresis of the lysed cell results in structures that resemble comets that can be seen via fluorescence microscopy. The intensity of the comet tail in comparison the head is a reflection of how many breaks there are in the DNA.