The increased levels of estrogen also make the mucus stretchy and clear. As the level of estrogen builds, another hormone, called lutein, is released. Lutein causes the ovaries to release the ovum. The estrogen levels decrease somewhat after ovulation, causing the mucus to dry up. This drying up process normally starts on or just after the day of ovulation.
Mucus has several purposes in the area of human reproduction.
First, it performs a lubricating function during sexual relations. Secondly, but more importantly, it provides a friendly environment for the survival of sperm after sexual relations have taken place. Without this environment, sperm would live no longer than several hours and would be literally stopped dead in their tracks, unable to move, unable to fertilize the waiting ovum. With mucus, sperm are provided with both nutrients and a vehicle for movement and may live up to five days in such an environment. Sexual relations taking place several days prior to ovulation may still result in conception due to the increased viability of the sperm in the mucus environment.