Toxicology Program, ILS, Inc. 1 article published in JoVE Genetics Use of Frozen Tissue in the Comet Assay for the Evaluation of DNA Damage Cheryl A. Hobbs*1, Leslie Recio1, John Winters1, Kristine L. Witt2 1Toxicology Program, ILS, Inc., 2Division of the National Toxicology Program, National Institute of Environmental Health Sciences This protocol describes several procedures for preparing high quality frozen tissue samples at the time of necropsy for use in the comet assay to assess DNA damage: 1) minced tissue, 2) scraped epithelial cells from the gastrointestinal tract, and 3) cubed tissue samples, requiring homogenization using a tissue mincing device.