The principle of the assay is based upon the ability of denatured, cleaved DNA fragments to migrate out of the nucleoid under the influence of an electric field, whereas undamaged DNA migrates slower and remains within the confines of the nucleoid when a Choose the Neutral CometAssay to detect double-stranded breaks or the Alkaline CometAssay for a more sensitive protocol used to detect smaller amounts of damage including single and double-stranded breaks Cells are immobilized in a bed of low melting poi