?You might believe that the fastest sperm will be the triumphant one in the fertilization process. It's certainly easy to compare the race of sperm to that of an Olympic swim match. However, recent research of the sperm of male fruit flies indicates that size instead of speed is the deciding factor in the sperm's ability to fertilize the egg.
According to a study soon to be published in Current Biology, scientists used male fruit flies which had been genetically modified so that they would produce glowing sperm. The scientists then separated the fruit flies into two groups, one whose sperm glowed red and one whose sperm glowed green. By using fruit flies with glowing sperm, scientists were able to watch the fertilization process as it took place more clearly.
Scientists in the study were interested in seeing how competition between sperm affected each individual sperm's behavior. They discovered that it didn't matter which of the individual sperm finished the race through the female's reproductive tract first, because all of the sperm were forced to wait in a separate storage department until the female fruit fly released her egg. When the female fruit fly mated with a new partner, the newly arrived sperm would try to kick the other sperm out of the storage compartment.
As a result of their study, the scientists concluded that being faster than the other sperm held no advantage in the fertilization process. In fact, they discovered th at sperm which were longer and slower were often able to eject the other sperm out of the storage area much more efficiently than their faster and smaller counterparts.
In other words, the rush to fertilize the egg is nothing at all like an Olympic swim match. The slow and steady sperm might win the day, providing that he is bigger than the other guys.
