 CatSper plays a key role in mediating hyperactive motility – prior to fertilization, sperm become entrapped within the fingerlike projections of the microvilli of the oviduct.In order for the sperm to fertilize the oocyte, CatSper must be present in order to initiate hyperactive motility, allowing the sperm to escape the microvilli and reach the oocyte for fertilization.Of the four members of the Catsper family, Catsper1 is found in the primary piece of sperm.