Fertilization in animals

Fertilization in mammalian and nonmammalian organisms has many features in common. These features include a final maturation phase for sperm and eggs, species-specific binding of sperm to eggs, penetration by sperm of one or more extracellular coals surrounding eggs, fusion of sperm and eggs, and ac tivation of eggs. implicit in this are a variety of basic molecular events, including receptor-ligand interactions, signalling cascades, specific prot eolysis, and nuclear transformations. Here, several of these events are add ressed for fertilization in animals as diverse as starfish and mice. Dev. G enet. 25.83-86, 1999. (C) 1999 Wiley-Liss, Inc.