When cells undergo apoptosis, specific DNA endonucleases will be activated, cutting the genomic DNA between the nucleosomes. After extraction and loading for electrophoresis, a DNA ladder of 180-200bp can be found in such DNA samples, which is a specific event during cell apoptosis. The exposed 3'-OH of the broken DNA can be catalyzed by Terminal Deoxynucleotidyl Transferase (TdT) with labeled dUTP, which can be detected with microscopy or flow cytometry.
Elabscience® One-step TUNEL Assay Kit is a highly sensitive, fast and simple method for cell apoptosis detection. The test results can be directly observed through a fluorescence microscope. This kit is suitable for in situ apoptosis detection of tissue samples (Paraffin embedding, freezing and ultrathin section) and cells (Cell smears, cell climbing smears) in situ apoptotic detection.