A double-blinded comparison of in situ TUNEL and aniline blue versus flow cytometry acridine orange for the determination of sperm DNA fragmentation and nucleus decondensation state index

The impact of sperm DNA fragmentation on assisted reproductive technology (ART) successes, in terms of outcome, is now established. High levels of DNA strand breaks severely affect the probability of pregnancy. The importance of sperm nucleus condensation in early embryogenesis and, subsequently, on the quality of the conceptus is now emerging. In this article we have compared in situ analyses with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL) (for DNA fragmentation) with aniline blue (AB) (for nucleus decondensation), versus flow cytometry (FC) after acridine orange staining, in a double-blinded analysis. In our hands, TUNEL and acridine orange give perfectly comparable results. For decondensation the results are also comparable, but the double-stranded green fluorescence obtained with acridine orange seems to slightly underestimate the decondensation status obtained with AB.