An update on human fertilization.

The process of fertilization and the role that each gamete plays in that process have been the subject of investigation in a large number of species and for many years. However, while much is now known for some species relatively little is known for others. Indeed, the specific events that are required to occur in the human male and female gametes and that facilitate fertilization are still somewhat ill-defined. For example, as of today, there have been numerous biomolecular processes that have been put forth as playing an important role in the sequence of events during which sperm acquire fertilizing ability, yet the actual significance of many of these remains suspect. This article will summarize what is presently best known about prefertilization processes occurring in human spermatozoa. For those interested in nonhuman mammalian and nonmammalian species, articles addressing this and other topics can be found in the many review articles cited herein.