Space conditions create barriers to reproduction

As humanity approaches the implementation of projects to populate the Moon and Mars, the question of the possibility of reproduction outside the Earth ceases to be the subject of theoretical research. New research has identified serious problems by simulating microgravity conditions.

Experiments conducted by Australian scientists, xrust writes, showed that microgravity conditions simulated in the laboratory disrupt sperm navigation, reduce the likelihood of fertilization and, when long-term exposure impairs the quality and survival of embryos in the early stages of development.

The researchers found that human and mouse sperm were about 50% less efficient at moving through a canal that mimics the female reproductive tract under these conditions compared to normal gravity conditions. In the case of mouse eggs, this resulted in a reduction in fertilization success of approximately 30%. The study also revealed complications in the early stages of embryo development.

The human body has evolved over millions of years to function optimally in the Earth's environment, including gravity, and travel beyond Earth causes many physiological changes that affect human health.

The United States, as part of NASA's Artemis program, plans to land astronauts on the Moon in the coming years. China is pursuing a similar goal.

Reproductive biologist Nicole McPherson, who leads the Sperm and Embryo Biology Group at the Robinson Research Institute at the University of Adelaide in Australia, said: “With the Artemis program actively working to return humans to the Moon and serious plans for manned missions to Mars, the ability to reproduce beyond Earth is fundamental to any long-term exploration of the planet.”

“This includes not only human reproduction, but also the animals and agricultural species upon which self-sustaining habitats depend,” she said.

Fertilization occurs when a man's sperm passes through the female reproductive tract and enters an egg, combining the genetic material of the two cells. A new study shows for the first time that gravity plays a critical role in a sperm's ability to move towards an egg.

McPherson explained: the ability to swim is not impaired. Sperm continue to move in microgravity, they just can't find their way. The navigation function, the ability to navigate and purposefully move towards a destination, appears to be impaired. We think this happens because many proteins on the surface of sperm act as mechanosensors, tiny molecular devices that detect physical forces, including gravity.

Interestingly, the addition of progesterone, a female hormone naturally released during ovulation as a chemical signal to help sperm find their way, helped more human sperm overcome the negative effects of microgravity.

Simulation of microgravity

To simulate microgravity, the researchers used a device that creates conditions for cells reminiscent of a continuous free fall in zero gravity in space. To test navigation ability, they used a plastic chamber with narrow channels, open at both ends, through which sperm had to pass from one end to the other.

Under microgravity conditions, there was an approximately 50 percent reduction in the number of human and mouse sperm successfully overcoming obstacles compared to normal gravity conditions.

The mice showed a 30 percent reduction in the likelihood of successful fertilization after four to six hours of microgravity compared to normal gravity conditions. Embryos that formed in microgravity appeared to be of higher quality and contained more cells that would eventually form into a fetus.

McPherson believes this suggests that short-term exposure to microgravity may act as a kind of selective filter through which only the most resistant sperm and embryos pass.

However, when developing mouse embryos were exposed to microgravity during the first 24 hours after fertilization—when genetic material from both parents first combines—fewer embryos were formed, and those that did form showed signs of delayed development and reduced cell numbers in the critical early stages.

Similar results were obtained when studying embryos using pig cells.

McPherson concluded: the most obvious conclusion is that reproduction in space will be much more difficult than most people assume. And these difficulties arise at several stages, not just at one.

By pages https://www.reuters

Xrust Outer space conditions create barriers to reproduction