Semen Assessments
Similar to the comet assay, the sperm chromatin dispersion (SCD), or ‘halo’ assay, assesses the extent of DNA fragmentation using fluorescent microscopy. Spermatozoa are immersed in an agarose matrix, and lysed to remove cell membranes, cytoplasm and nucleoplasm. Cells are subsequently treated with acid solutions to solubilise nuclear packaging proteins, causing the tightly compacted, intact DNA to spring outwards, resembling a halo-like structure around the nucleoid. The DNA is then stained with the nuclear marker (4′,6-diamindino-2-phenylindole; DAPI), visualised under fluorescent microscopy and graded based on halo size. Intact DNA will form large halo-like structure, while heavily fragmented DNA will produce little or no halos [1-3]. High DNA fragmentation assessed using the SCD assay is associated with decreased fertility and compromised embryo health [4, 5].
1. Absalan, F., Ghannadi, A., Kazerooni, M., Parifar, R., Jamalzadeh, F., and Amiri, S. (2012) Value of sperm chromatin dispersion test in couples with unexplained recurrent abortion. Journal of Assisted Reproduction and Genetics. 29(1): p. 11-14.
2. Fernández, J.L., Muriel, L., Goyanes, V., Segrelles, E., Gosálvez, J., Enciso, M., LaFromboise, M., and De Jonge, C. (2005) Simple determination of human sperm DNA fragmentation with an improved sperm chromatin dispersion test. Fertility and Sterility. 84(4): p. 833-842.
3. Fernandez, J.L., Muriel, L., Rivero, M.T., Goyanes, V., Vazquez, R., and Alvarez, J.G. (2003) The sperm chromatin dispersion test: a simple method for the determination of sperm DNA fragmentation. J Androl. 24(1): p. 59-66.
4. Muriel, L., Meseguer, M., Fernández, J.L., Alvarez, J., Remohí, J., Pellicer, A., and Garrido, N. (2006) Value of the sperm chromatin dispersion test in predicting pregnancy outcome in intrauterine insemination: a blind prospective study. Human Reproduction. 21(3): p. 738-744.
5. Velez de la Calle, J.F., Muller, A., Walschaerts, M., Clavere, J.L., Jimenez, C., Wittemer, C., and Thonneau, P. (2008) Sperm deoxyribonucleic acid fragmentation as assessed by the sperm chromatin dispersion test in assisted reproductive technology programs: results of a large prospective multicenter study. Fertility and Sterility. 90(5): p. 1792-1799.