Factors which influence sperm ability to fertilize.

Different factors influence animal sperm ability to fertilize. Some of them are reviewed here, sperm motility, block to polyspermy, chemioattraction, sperm competition for fertilization. Old and new data are reported, as for example the new notions on sperm motility derived from site directed mutagenesis in rodents, the new notions on the odour receptors in mammalian sperm attraction and new notions on sperm competition, which is variable in different species.