Embryonic Stem Cells Used to Create Mice

British scientists have converted embryonic stem cells into sperm and used them to grow live mice, a feat that could lead to new treatments for fertility, the team reported in the journal Developmental Cell.

Out of 256 attempts, seven mice resulted from the work, with six living long enough to reach adulthood.

However, the animals were unusually small or large and died within five months of birth, apparently because they lacked normal controls over gene activity.