Contemporary aspects of male gamete (dys)function: aiming towards optimizing the treatment of fertilization disorders

At its inception, in vitro fertilization (IVF) was a relatively straightforward procedure encompassing the in vitro insemination of surgically retrieved oocytes and the trans-cervical uterine placement of the ensuing embryos with the goal of overcoming tubal infertility. Since that time, IVF has become the ultimate treatment modality for all infertility indications when standard treatments have failed. While IVF has revolutionized our clinical armamentarium, it has also served as a remarkable scientific tool allowing direct visualization of male and female gamete interaction and assessment of human embryo development, thus enabling reproductive specialists to dissect and better understand the early human reproductive processes. In its earliest stages, IVF was directed at the treatment of female infertility focusing on the role of the oocyte, later to be eclipsed by assisted fertilization techniques that revolutionized the treatment of male factor infertility. The advent of assisted fertilization techniques, from the most simplistic approaches to direct sperm injection, has made it possible for suboptimal male gametes to penetrate the oocyte vestments. The latter technique has shed light on the ultimate function of the spermatozoon and the fascinating process of syngamy. Moreover, the ability to temporally monitor the cleaving embryo in vitro has enabled us to ascertain the individual steps involved in the development of the conceptus from syngamy to blastocyst as well as to shed light on hitherto unapproachable infertility etiologies.