ABSTRACT
Fertilization is a sophisticated process for the production of offspring. Successful fertilization requires that sperm respond to various activation signals at the correct time and correct sites. The signals mediate sperm-egg interactions and induce initiation and activation of motility, chemotaxis and the acrosome reaction in sperm. The molecular mechanisms underlying the induction of these events have been reviewed in Ward and Kopf (1993). The sperm-egg interaction is induced at the egg-jelly coat surrounding the egg. Thus, the environment around the egg easily influences it. For example, although sperm-egg interactions are generally induced at the egg-coat, various species have made modifications with respect to the location of these interactions and the extracellular signals involved in them.
