Though some of these ubiquitin tagged spermatozoa may disintegrate and be removed in the epididymis, many appear in the ejaculate,
and their increased content is indicative of poor semen quality or even infertility.
32,34 Increased binding of fluorescently labeled anti-ubiquitin antibodies to the sperm surface reflects the occurrence of sperm abnormalities (Fig. 1C).
This can be detected by flow cytometry as an increase in the relative fluorescence induced due to the presence of ubiquitin on the sperm surface.