Mammalian Fertilization Is Dependent on Multiple Membrane Fusion Events*

Successful completion of fertilization in mammals is dependent on three membrane fusion events. These are (1 ) the acrosome reaction of sperm, (2 ) the fusion of sperm and egg plasma membranes to form a zygote, and (3 ) the cortical reaction of fertilized eggs. Extensive research into the molecular basis of each of these events has identified candidate proteins and factors involved in fusion of membranes during the mammalian fertilization process. Some of this information is provided here.