If humans are going to colonize space, reproducing in a zero or low gravity environment may be a necessary condition. It has been known for decades, though, that some animals fail at pregnancy while aboard orbiting spacecraft. Japanese scientists from the RIKEN Center for Developmental Biology in Kobe decided to look into which part of the fertility process is affected by a lack of terrestrial gravity. They used a device called a 3D clinostat (pictured) which revolves around an axis to create a microgravity environment in which to do the experiments.
They performed in vitro fertilization (IVF) experiments with mouse sperm and ova, both within the clinostat and at regular gravity (1G), and determine that microgravity had minimal effects on fertilization. It may prove detrimental to subsequent development, however. Microgravity-cultured embryos successfully reached the two-cell stage and yielded viable offspring upon implantation into female mice, but at a significantly lower rate than their 1G counterparts. The researchers observed more severe negative effects when embryos were transplanted following longer culture periods in the clinostat.
Microgravity led to an overall reduction in the rate of blastocyst formation after 96 hours of culture, and closer examination of these blastocysts revealed that the differentiation of embryonic cells into trophectoderm—the tissue that nourishes the embryo and ultimately contributes to placenta formation—was markedly impaired.
Given the successful development of non-mammalian embryos in microgravity, these findings were surprising, and Wakayama and colleagues intend to pursue further gravity-manipulation studies to zoom in on the source of the developmental problem. “We are planning to perform similar experiments at different gravities, such as Moon gravity (1/6G) or Mars gravity (1/3G),” he says. “I want to know how much gravity is necessary to perform normal reproduction.”
Full story: Embryonic development–lost in space?
Article in PLoS ONE: Detrimental Effects of Microgravity on Mouse Preimplantation Development In Vitro