[The TUNEL technic for demonstrating apoptosis on paraffin sections].

TUNEL technique, i.e. terminal deoxynucleotidil transferase-mediated dUTP nick end-labeling, has become a widely used staining method to assist in detection of apoptotic cells in tissue section for routine pathology and scientific investigation. Terminal deoxyribonucleotidyl transferase catalyzed the addition of biotinylated dUTP to free 3'OH ends of DNA fragments, with the synthesis of a polydeoxynucleodide polymer. The signal is amplified by avidin-(biotin)-peroxidase and diaminobenzidine is used as chromogen. We have used this technique to study apoptosis in a group of 9 patients with primary breast carcinoma, 4 of them treated with primary chemotherapy. In situ labeling technique identify apoptotic cells, including those with early nuclear chromatin margination. Necrotic cells have multiple random DNA breaks and stain less intensely. Using these technique will allow for the comparison of the quantitative rate of apoptosis in specific target cell types before and after therapy. Such comparison should enhance knowledge as to the role that apoptosis plays in process of cancer therapy.