Scientifically speaking, sperm capacitation is a natural and essential process when a woman’s natural conception lubrication dissolves the immobilizing cholesterol from the sperm and creates an enzyme to allow the sperm to fertilize the ovum.
In layman’s terms, sperm capacitation occurs when the lubrication a woman produces when sexually aroused removes the outer layer around any sperm entering the vagina and heading up the fallopian tube. Removal of the outer layer and the addition of an enzyme must take place for the sperm to be able to fertilize an egg.
Capacitation allows the sperm to move with whip-like motions to travel the six to seven inches into the ampulla, the far end of the fallopian tube where the mature egg is released by the ovary each month. Capacitation also allows the sperm to penetrate the egg for conception.
In-vivo sperm capacitation occurs when the sperm is properly capacitated in the women’s cervix. In-vivo sperm capacitation selects out immature and abnormal sperm that lack capacitation. The process also selects out sperm coated with anti-sperm antibodies or strips off those antibodies to allow for proper capacitation.
In-vivo sperm capacitation works to allow only the fittest sperm to fertilize, but can only do so with normal vaginal lubrication.
Assisted reproductive procedures require sperm capacitation:
Sperm are capacitated for several hours in the laboratory test tube before egg fertilization. The IVF procedure was only successful because of the discovery of laboratory sperm capacitation in 1970.
In 2009, Dr Pablo Visconti in the article Understanding the molecular basis of sperm capacitation through kinase design, in the "Procedings of the National Academy of Sciences of the United States of America" stated that "In Vitro Fertilization was made possible with the discovery of Sperm Capacitation."