Natalie1982, please don't be offended - I wasn't poking fun at you and I appreciate that the workings of a man's bits are a mystery to many. Because of this, I'd be the first to agree that's it's a valid question on AB
What I found amusing was the concept of semen moving forward in an external environment due to the movement of the sperm it contained. I know it can't occur, yet I should have explained some of the reasons why.
Basically, in a any given sample of semen, there are three different types of sperm present as far as locomotion is concerned. The first, is the small percentage of dead sperm that occur in all ejaculate, which obviously don't move at all. The second type are sperm that appear to be going crazy and move in a more or less random circular or spiral path and don't go in any direction fast. The third type is sperm that travel in virtually straight lines thus taking the shortest possible route through the semen from one side to the other.
Now male fertility generally speaking, is measured in terms of the percentage of the third type of sperm present. These sperm don't hang around and head off in the direction of the egg at great speed leaving the crazy moving sperm and dead sperm far behind. In fact, if you've seen the film "Look Who's Talking" with John Travolta, their movement is exactly like that portrayed at the beginning of the film!
The opposite scenario where a man has greater than about 25% of crazy moving sperm means that his fertility is reduced and this figure can rise to virtually 100% in some men. Psychologically, it's a particularly difficult situation as the man is effectively impotent yet has sperm in his semen.
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