Not the fastest sperm will win

Just fast is not enough, it needs to be big and long.

As we know, in the process of fertilization sperms must compete in a very fierce race to be able to fertilize eggs. Previously, scientists believed that the fastest sperm would have a higher chance of winning. However, a recent study shows that just being fast is not enough, the deciding factor that a hostage has a high chance of fertilizing eggs is the length.

New research from the University of Sheffield has demonstrated that longer spermatozoa are more likely to combine with eggs during fertilization. Scientists have experimented on zebra finches. In the animal world, sperms must not only compete with rivals of the same male, but they must also compete with the sperm of other males. Because a female can mate with many different males.

Zebra finches are chosen for a particular feature, which is the degree of refinement in an individual that is consistent but different individuals change. The researchers first divided two groups of males, group one with spermatozoa of less than 60 micrometers, and group two with sperm length over 70 micrometers.

Then the two groups of males are mated with females, each of which is mate with both males of the two groups. In particular, the first group is allowed to mate before the second group. It also means that the sperm of group one has the advantage of being mated first.

However, after both groups were mated, the scientists followed the fertilization process and found that the sperm were longer than the second group, although it was later but had a delivery rate. mix with higher eggs. The scientists then conducted an additional blood relation test and found that the number of fathers in the second group was more than twice that.

This result shows that although the sperm of the second group are fertilized later but still capable of combining with higher eggs. Scientists have not been able to explain this yet, because the sperm process coming together with eggs still has a lot of mysteries.

The head of the research project Clair Bennison said: 'This result has proved completely different from what we have known before. Although there are differences between humans and birds, fertilization is, in principle, the same in animals. "

Scientists predict that larger sperm will have a better chance of surviving on the road to combine with eggs. Because not all sperm can reach the egg, many sperm die on this road. This result can also be part of natural selection, when mating with many males, the sperm of the strongest males can have higher fertility.

Reference: discovermagazine.