The procedure involves embedding cells in agarose on a microscope slide, lysing them to remove membranes and proteins, and then subjecting the DNA to electrophoresis. Under an alkaline condition, the broken DNA strands migrate out of the cell nucleus, forming a tail. The extent of DNA migration is proportional to the amount of damage. This "comet" is then stained and visualized using a fluorescence microscope. The tail length and intensity are measured to quantify the DNA damage.
