Many space age dreams involve humans spreading out into the far reaches of the galaxy, but our extraterrestrial breeding program might need a little help. Scientists in Japan have found microgravity may function as a form of birth control.
A paper published in this week's Public Library of Science ONE examined the obstacles to mammalian reproduction in space. While frogs, salamanders, and sea urchins all have proven records of extraplanetary fertility, mammals sent to space have not fared so well in the breeding department.
The team of Japanese biologists decided to investigate the impact of low gravity on mammalian embryonic development. They stored mouse eggs and sperm inside a three-dimensional clinostat, a device that mimics the effects of weightlessness, and then fertilized the eggs, allowing some to develop inside the clinostat and others to develop in normal gravity.
They found that, while fertilization occurred normally in the simulated microgravity, embryos that continued to develop in the clinostat had more difficulty dividing and maturing than those developing in normal gravity. Some of the embryos did survive and were implanted in mice, but they survived in much lower numbers than the embryos that were fertilized in the clinostat but developed outside it (no word on the relative health of the mice that were ultimately born). And the experiment suggests that mammalian embryos are especially sensitive to changes in gravity, and that it might be difficult for humans to reproduce in places where the gravity does not resemble Earth's.