How the Body Works: Sperm Transport

There are more than 350 million sperm in a single ejaculate, but only one sperm fertilizes an ovum. In the vagina the mucus in the semen must be dissolved by enzymes before the sperm can move. The initial reduction of sperm occurs at the cervix and about one million sperm enter the uterus. Uterine contractions carry the sperm toward the Fallopian tube, but only one thousand enter. Although about one hundred sperm reach the ovum, only one sperm fuses with its nucleus.