TerminalDeoxynucleotidylTransferase(TdT)catalyzestheincorporationofsingledeoxynucleotidesintothe3"-OHterminusofsingle-ordouble-strandedDNA,makingitaneffectiveagentin3"endlabelingapplicationssuchasTerminaldUTPnickendlabeling(TUNEL).TerminalDeoxynucleotidylTransferase(TdT)requiresanoligodeoxynucleotideofatleastthreebasesasaprimer,butisnottemplate-dependent.