This is the change that sperm must undertake to acquire the capacity to fertilize an ovule. Naturally this happens when the ejaculate travels through the cervix and enters the uterine cavity. This can be achieved artificially in a laboratory through techniques such as swim-up or density gradients.
In these techniques the more fertile sperm is separated from the seminal fluid, choosing a sample that is then used to conduct the intrauterine insemination or the in vitro fertility techniques. This technique also allows us to analyse the recount of moving sperm (REM) that helps determine the best treatment for each couple.