Numerical chromosome abnormalities are associated with sperm tail swelling patterns

Objective: To assess whether the differential sperm tail swelling patterns observed following hypo-osmotic shock are useful in discriminating normal sperm from aneuploid sperm. Design: Prospective study. Setting: University research setting. Intervention(s): Fluorescence in situ hybridization (FISH) was combined with hypo-osmotic swelling for a simultaneous assessment of aneuploidy and viability in human spermatozoa. Main Outcome Measure(s): FISH for chromosomes 1, 13, 18, 21, X, and Y after hypo-osmotic stress was used to investigate the distribution of sperm aneuploidy related to sperm-tail swelling patterns. A total of 16,473 sperm cells were scored from three normal fertile donors and six oligoasthenoteratozoospermic (OAT) patients. Result(s): There was a 17.2-fold decrease in the frequency of total aneuploidy in the sperm with a tail-tip swelling pattern compared with the initial nonselected sperm in the OAT patients. Strikingly, when the sperm with tail-tip swelling patterns were screened from the patients, the frequency of total aneuploidy was actually lower by a factor of four than in the nonselected sperm from fertile donors. Conclusion(s): The sperm cells with tail-tip swelling patterns are related to a low frequency of aneuploidy.