After new studies revealed that cooperation is a stronger reproductive motivation than survival of the fittest, the old adage that the fastest, strongest sperm fertilises the egg is being questioned.
Male sperm must travel a long, difficult distance through the female reproductive system, and they have a significantly better chance of reaching the egg if they swim in clusters, according to researchers from Cornell University and North Carolina A&T State University.
The researchers discovered that sperm travel in groups as they go through the uterus, fallopian tubes, and cervix’s thick yet elastic fluid toward the egg.
Similar to schools of fish, sperm swim autonomously but enter and exit the group as they go. The researchers conducted tests using bull sperm, which has qualities similar to those of human sperm, to determine whether this collective swimming had any real biological benefit.
The researchers studied how the sperm responded when they changed the fluid’s and flow’s physical characteristics after placing the sperm in a device that replicated the cervix and uterus. Their findings were published in Frontiers in Cell and Developmental Biology. They identified three advantages of sperm travelling in clumps as opposed to individually.
The sperm can more successfully swim in a straight line when they are grouped together while the fluid is static, meaning there is no flow at all. When there is a modest flow, clustering aids the sperm in aligning with one another so they can swim upstream like a school of fish. Sperm that are swimming together while the flow is at its strongest are less likely to be swept away by the stream.
Scientists can utilise the findings regarding sperm mobility to better understand why certain sperm may not survive and to increase the chances of conception in couples who are having trouble getting pregnant. The more knowledge scientists gain about which sperm are most effective at reaching the egg, the more they can use that knowledge to improve assisted reproductive technology, which helps people conceive children.