Effect on Sperm DNA Quality Following Sperm Selection for ART: New Insights.

In the female reproductive tract, male gametes undergo a natural sperm selection process in order to discriminate spermatozoa on the basis of their quality to maximize the chances of successful reproduction. With the introduction of assisted reproductive technology (ART), scientists and clinicians developed diverse sperm selection strategies focusing on the isolation of competent spermatozoa. With increasing understanding of sperm functions and fertilization mechanism and evolution of available technologies, the initial simple sperm preparation protocols were complemented, and sometimes replaced, by new sperm-sorting techniques. In particular, while in the early years the focus was on obtaining motile spermatozoa, in later years, especially after the introduction of intracytoplasmic sperm injection (ICSI), the focus shifted to the isolation of functional and "healthy" spermatozoa, considering some other important factors, such as sperm DNA integrity. Sperm DNA damage, as well as chromatin structure alterations, in fact, is related to decreased reproductive ability of men, in natural as well as in assisted reproduction.