1.  Couples have mixed feelings about these microscopic balls of cells.

2.  Others, including this page, consider the blastocysts to be microscopic balls of cells that have no chance of becoming human in a petri dish outside the womb.

3.  Scientists dispute his interpretation, saying that the retrieval is conducted when an embryo is only a week old, and still a microscopic ball of identical cells.

4.  Scientists dispute his interpretation, saying the retrieval is conducted when an embryo is only a week old, and is still a microscopic ball of identical cells.