Sperm capacitation is a natural process that sperm undergo in the female reproductive tract that enables them to penetrate and fertilize an egg. It is a prerequisite for fertilization, and only capacitated sperm have the exclusive ability to undergo acrosome reaction and subsequently fertilize an egg. Capacitation is the penultimate step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte. The process of capacitation causes a series of changes in sperm’s biochemical composition and structure such that they develop increased motility and are prepared for interactions with the egg at fertilization. Capacitation has two effects: destabilization of the acrosomal sperm head membrane which allows it to penetrate the outer layer of the egg, and chemical changes in the tail that allow greater mobility in the sperm. The changes are facilitated by the removal of sterols (e.g. cholesterol) and non-covalently bound epididymal/seminal glycoproteins, resulting in a more fluid membrane with increased permeability to Ca2+ ion.