But once you were a viable embryo, she was locked out of the process.

"I had Singh do up a viable embryo, and it's ready for implanting any time."

It is helpful to remember that, even for fertile people, nature does not produce a viable embryo every month.

We now have four perfectly viable embryos, and the first will be transplanted in a week.

The process can be repeated several times, though the maximum number of viable embryos possible is 96, with 72 being a "good average".

The first batch of viable embryos were produced today.

This new technique could ultimately give parents and doctors a preview of which eggs are likely to make the most viable embryos.

We are conditioned to react rather peculiarly to the idea that a nearly viable embryo may think.

The only restrictions are that the cells should not be made into viable embryos or used for human cloning.

This produced 11 viable embryos, of which 4 were implanted without result, leaving the 7 still frozen.