The theory that patients with type I diabetes can eat anything they wish as long as they adjust their insulin intake was first developed in Germany.

BBC: Diabetics 'freed from strict diets'

Under the right conditions, these cells can replenish themselves indefinitely in the laboratory, and they can, in theory, turn into any type of cell in the body.

NPR: Making Sperm, No Men Necessary

Theory suggests that a certain type of giant, short-lived star can experience catastrophic collapse when the nuclear reactions at its core can no longer support its mass.

BBC: Telescope spies cataclysmic blast

In order to be useful to scientists, cells derived from embryos also must be able to divide almost endlessly and be able to turn into any type of human tissue, at least in theory.

FORBES: Magazine Article

Embryonic stem cells are seen by many researchers as having great potential because they can in theory be coaxed to create any kind of cell type in the body.

FORBES: Stem Cells' Double Breakthrough