To reach the ovum, sperm cells have to run the gauntlet of many hazards. The cervix has many defenses to prevent infection entering the womb and hurting either the mother or the baby. Many sperm cells find themselves stuck up a blind alley such as this one. They will die and be consumed by the mother’s immune system.
This obstacle course ensures that only the healthiest sperm enter the womb to find their way to the fallopian tubes and the ovum.
This is a silicon model of the cervix and the fallopian tubes made for the Discovery Channel program: “Curiosity: Life before Birth” produced by Pioneer Productions. The sperm cells are hand animated.
This video can be found in the David Barlow Film Archive at;