Space Screws Up Sperm’s Ability to Navigate Properly

Humans may be living on the Moon sooner than expected. Earlier this week, NASA Administrator Jared Isaacman announced an advanced timeline for the agency’s plans to return to the Moon and establish a permanent base there. If these projects come to fruition, it will mark a major milestone in manned space exploration. While we already know that humans can live and work in microgravity (with major help from technology), what about the next frontier: successful reproduction? New research published today in Communication biology tackles this question by studying how sperm function in microgravity.

Researchers at the University of Adelaide in Australia placed sperm samples from mice and humans in mazes mimicking the female reproductive tract and loaded them into a machine to simulate weightlessness. Known as a 3D clinostat, this machine features two continuously rotating frames on different axes that keep cell cultures in constant motion to simulate space conditions. After several hours of spinning in the clinostat, the researchers checked their progress.

So how did the little swimmers fare? Not great.

“We observed a significant reduction in the number of sperm able to make their way through the maze of chambers in microgravity conditions compared to normal gravity,” study author Nicole McPherson said in a statement.

Read more: “Should people live on the Moon?

Although the microgravity conditions did not affect the sperm’s ability to swim, it did interfere with their ability to navigate. That said, adding a little progesterone, a sex hormone released by the egg, seems to strengthen their sense of direction.

The team also studied the effects of microgravity on the fertilization of mouse eggs, noting a 30 percent reduction after four hours of rotation in the clinostat.

“We observed a reduction in fertilization rates during four to six hours of exposure to microgravity,” McPherson said. “Prolonged exposure appears to be even more detrimental, leading to developmental delays and, in some cases, a reduction in the cells that will form the fetus from the earliest stages of embryo formation.”

However, some healthy embryos were able to form, even if they were conceived in microgravity conditions. “This gives us hope that reproduction in space will one day be possible,” McPherson said.

The team next plans to study other gravitational environments, such as those found on the Moon and Mars, to determine whether the decline in fertilization is gradual or if there is a threshold effect. We may very well have a permanent base on the Moon by then, but the first lunar babies won’t be born for some time.

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Main image: supplement / Adobe Stock