Using homologous recombination, we have previously produced male mice carrying a
disruptive mutation (Acr−/−) in the acrosin gene. Although Acr−/− mouse sperm lacking the
acrosin protease activity still penetrated the zona pellucida and fertilized the egg, the mutant
sperm exhibited a delay in penetration of the zona pellucida solely at the early stages after
insemination. To further elucidate the role of acrosin in fertilization, we have examined the
involvement of acrosin in the acrosome reaction of sperm using the Acr−/− mutant mice …