J. Clin. Invest. 120: 984-994 (2010)

Mammalian sperm migrate through the female reproductive tract and fertilize eggs in the oviduct. Using gene knockout approach, numerous factors considered to be important during fertilization have been challenged for their significance. Surprisingly, most of them were turned out to be dispensable. This Review focuses on the advantages of studying fertilization using gene knockout animals and highlights an emerging molecular mechanism of mammalian fertilization.