Slower sperm that swim in teams give higher chances of pregnancy than speedier loners

Teamwork makes the dream work.

Oct. 14, 2022

Slower sperm that swim in teams give higher chances of pregnancy than speedier loners

Turns out, teamwork could actually be part of our DNA.

Scientists studying bovine sperm recently discovered that the reproductive cells stand a bigger chance of succeeding when they swim together as a group.

This is contrary to previous findings, where speedier and stronger sperm cells often lead to the creation of a baby, physicist Chih-kuan Tung and his team found. The discovery was reported in Frontiers in Cell and Developmental Biology on September 22, 2022.

“They are not faster,” Tung, of North Carolina Agricultural and Technical State University in Greensboro, said of the sperm that swim in clusters. “In terms of speed, they are comparable or slower," he was reported as saying in Science News.

Instead of being fast, these sperm are the ones that stay on target. Loner sperm follow a curved path but this poses a problem since the shortest distance between two points is a straight line.

However, when sperm swim in groups of two or more, they tend to swim straight.

The team of researchers tested their theory by creating an experimental setup where flowing liquid was introduced. The idea was to mimic the experience of swimming in an ovum, where sperm often have to swim against a current of mucus through the cervix and uterus.

Tung and his team built a four-centimeter-long shallow but narrow channel and filled it with fluid that mimicked the ones found in the cervix and uterus. The team also made sure that they were able to control its flow so as to be as authentic to nature as possible.

This is when they learned that sperm swimming as a team, were able to swim upstream. Meanwhile, individual sperm often swim to other directions despite their speed.

When the flow was turned up, many loners were washed away. However, the sperm that swam in groups survived.

Although the discovery was made on bull sperm, the team believes similar advantages could apply to human sperm since both species have similar sperm dimensions. Furthermore, both human and bovine sperm are deposited in the vagina and travel through the cervix, making their way to the uterus.

Tung believes their research could help scientists understand infertility in humans.

Fertility researcher Christopher Barratt of the University of Dundee in Scotland, who played no part in the study, said Tung's discovery was an important one.

“How a sperm cell responds to its surroundings and how that may change its behavior is a very important subject. This type of technology could be used, or adapted, to select better quality sperm. "That would be a very big deal," Barrat said.

If ever anyone rubbishes teamwork, show them this.