When it comes to the motion of sperm, it is not absolutely man for himself. Instead, sperm form groups or clusters that swim together through gloopy fluids, researchers observed.
After studying the motion of sperm, a team of researchers from the North Carolina AT&T State University found evidence that sperm cells tend to move closer together when swimming in viscoelastic fluids.
In order for sperm to make it to the egg cell, they must swim inside the vagina and pass through the cervix and uterus until they reach the fallopian tubes, where a sperm will fertilize a waiting egg. This is the case for humans and other mammals.
The fluid inside the reproductive tract is not thin or diluted like water but it has certain levels of viscosity. Some parts of the fluid is viscoelastic, which means it is elastic.
To observe the movement of sperm in fluids, the researchers obtained bull sperm samples and placed them in various fluids in the laboratory.
They found that the sperm swam independently in all of the fluids except for those that are viscoelastic. The team noted that there are similarities when it comes to sperm grouping and the way molecules behaved.
"If you look carefully, you can see that it's a very dynamic process," Chih-kuan Tung, an assistant professor from North Carolina A&T State University explained.
"There will be new cells joining in to the group, and there will be cells leaving the group at the same time," he added.
The team is yet to uncover the reason why viscoelasticity is important for the sperm.
"Right now ... they just mix sperm and egg in a tube and hope they meet each other," Tung said. He proposed that one way to improve the likelihood of in vitro fertilization (IVF) success is to give the sperm the same obstacle course they encounter naturally.
The researchers believe they found an important tool for studying collective behavior.
"Collective dynamics in biology is an interesting subject for physicists, in part because of its close relations to emergent behaviors in condensed matter, such as phase separation and criticality," the researchers wrote.
The team presented their findings on March 17 at the March Meeting of the Americans Physical Society in Baltimore.
Photo: Andrea Laurel | Flickr
