Ratio of X to Y-Chromosome Bearing Spermatozoa: Variation Within and Between Donors

The aim was to evaluate the ratio of X- to Y- Chromosome bearing sperm variation within and between the ejaculates from five sperm donors. Five separate ejaculates, and corresponding buccal swab samples, were obtained bi- or tri- weekly from each of the donors and the DNA extracted and quantitated using qPCR to determine the ratio of X- to Y- Chromosome bearing sperm in each ejaculate in relation to the respective buccal swab DNA. Since the sum of the percentages of X and Y chromosome bearing sperm in an ejaculate equals 100, the results of the percentages of Y chromosome bearing sperm are identically opposite to the percentages of X chromosome bearing sperm. Therefore, only the percentages of Y chromosome bearing sperm are expressed hereafter. The overall mean percentage of Y- Chromosome bearing sperm from one donor was significantly different (p < 0.05) from three others and the variation within each donor ejaculate was within its own 95% confidence interval of the mean for that donor. The variation of the Y-chromosome bearing sperm between donors was significant but not within each donor, suggesting that the ratio of X- to Y- Chromosome bearing sperm is consistent for each donor.