During a two week unmanned biology satellite mission, Chinese scientists successfully demonstrated that mouse embryos can develop in weightlessness.
The team developed an embryo culture system and placed it within a small enclosed chamber [on the spacecraft] that provides the ideal conditions for the embryos to develop in space. While the chamber was in orbit, a camera attached to the experiment took photographs of the embryos as they developed in microgravity, and sent these images back to Earth. With the aid of their imaging technology, the researchers were able to observe how the mammalian two-cell stage embryos developed into blastocysts under microgravity after four days. Blastocysts are structures formed in the very early development of mammals. In humans blastocysts begin to form five days after fertilization.
The researchers will now compare their space-developed embryos to those cultured in normal laboratory environments on Earth to see what differences there are between the two at both a cellular and molecular level.
None of this proves that life can be conceived and grow in weightlessness. It does however suggest that it might be possible.