Sperm DNA fragmentation consists of single- and double-DNA strand breaks in the nuclei of spermatozoa and represents a semen parameter that can improve the diagnostic ability of routine semen analysis in a male infertility workup. Among the available tests detecting sperm DNA fragmentation, TUNEL assay is very popular because it is easy and rapid to execute. However, many variants of this test exist making it difficult to compare the measurements among different laboratories. One main advantage of TUNEL is that it allows for the use of flow cytometry and to simultaneously detect sperm DNA fragmentation with other cell features. A novel version of TUNEL, termed TUNEL/PI, couples sperm DNA break detection with nuclear staining ameliorating the accuracy of flow cytometric measures of sperm DNA fragmentation and revealing two sperm populations, brighter and dimmer, with a different extent of DNA breakage. The brighter fraction of sperm DNA fragmentation is a promising predictor of male infertility and a more sensitive measure of change in DNA breakage during sperm selection for in vitro fertilization.
KeywordsTUNEL Sperm DNA fragmentation Flow cytometry Male infertility
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