Renovation of the egg extracellular matrix at fertilization.

Extracellular matrices are essential for cell survival and function. This is especially relevant for eggs, which establish a physical barrier at fertilization to protect a new embryo from additional sperm and pathogens. Formation of an extracellular matrix is most dramatic in sea urchins, in which fertilization was first observed in animals with the "sudden appearance of a perfectly transparent envelope" (A. Derbes, 1847). The process of assembling this extracellular "envelope" has been a topic of intense study ever since. Here we integrate the cellular and molecular events necessary to form this fertilization envelope within the first few minutes of a new embryo's life.