Terminal deoxynucleotidyl transferase (TdT) dUTPNick-EndLabeling (TUNEL) assay has been designed to detect apoptotic cells that undergo extensive DNA degradation during the late stages of apoptosis. The method is based on the ability of TdT to label blunt ends of double-stranded DNA breaks independent of a template. This chapter describes an assay for detection of apoptotic cells during mouse odontogenesis using a colorimetric TUNEL system.
