In the TUNEL assay, TdT enzyme catalyzes the addition of labeled dUTP to the 3'- ends of the internucleosomal DNA strand breaks that are a hallmark of apoptosis. The CF® dye TUNEL Assay Apoptosis Detection Kit employs dUTP conjugated to Biotium's exceptionally bright and photostable CF® fluorescent dyes, for single step fluorescent TUNEL labeling of fixed cells or tissues for analysis by fluorescence microscopy or flow cytometry. The kit is available with the following CF® dyes: green fluorescent CF®488A, red fluorescent CF®594, and far-red fluorescent CF®640R.