Each type generates replacement cells for the particular tissue in which it is found.

If so, the replacement cells would not necessarily be destroyed.

Dr. Eggan, though, is not after replacement cells.

"It is one of the things that made people much more ambitious and optimistic" about using stem cells as replacement cells for humans.

In the adult body, many tissues generate replacement cells from a private niche of stem cells.

Cloning is an arduous process, and using it to create tailor-made replacement cells may prove impractical.

Downsides are initial cost of the system, maintenance, and the cost of replacement cells.

Standard-capacity batteries are also available, as are replacement cells for last year's third-generation iPods.

We hope to achieve the restoration, perhaps permanently, of organ function by the injection of replacement cells.

They may offer a renewable source of replacement cells to treat diseases, conditions, and disabilities.