[Sperm reservoir in mice: involvement of ADAMs]

Mammalian sperm migrate over long distances through the female genital tract before reaching the oviduct where fertilization occurs. This process is more complex than predicted by the movement of sperm. The oviduct is composed of three major segments: the uterotubal junction, the isthmus and the ampulla. These structures appear to play roles for the success of fertilization. Gene knockout approaches of several genes in mice suggest that the migration of spermatozoa in the oviduct is regulated to allow competent gametes encounter ensuring the success of fertilization with minimum risk of polyspermy. The sperm of male mice deleted for following genes: Calmegin, Calsperin, Angiotensin-Converting-Enzyme, Adam1a, Adam2 or Adam3 are morphologically normal and motile, but not able to pass through the uterotubal junction. The precise mechanism of how these molecules facilitate the passage of spermatozoa through the uterotubal junction is still unknown, but Adam3 seems to be the major factor in this process since it is implicated in these six lines of mutant mice.