Once an acrosome reacted sperm comes in contact with the egg, a series of events are initiated that culminate in the union of the genetic material. We can separate these steps into (1) species-specific sperm-egg binding, (2) the fast block to polyspermy, (3) the slow block to polyspermy, (4) sperm incorporation, and (5) pronuclear migration and fusion. The next several pages deal with these topics. On this page, an animated summary of these events is available, courtesy of Dr. David Epel, as well as a QuickTime movie of fertilization envelope formation in L. variegatus (produced by Ted Shinners, who at the time was an undergraduate student in the Hardin lab).
QuickTime movie (260 K) Animated GIF
QuickTime movie (423K)