Cervical mucus

n. A substance found inside a woman's vagina near her cervix that can either aid or impede insemination. When the mucus is dry and thick, it creates a barrier for sperm. When the mucus is moist and thin, it preserves and propels sperm. Studies have shown that cervical mucus responds differently based on the genetic makeup of the sperm. It accepts the compatible sperm from a superior male and rejects the incompatible sperm from an inferior mate.