In article <Pine.SOL.3.91.950424221102.11986A-100000 at corona>, Patrick
O'Neil <patrick at corona> wrote:
> Theoretically, there is nothing impossible about regenerating a limb or
> even an organ...such is among the possibilities from future biotechnology.
> Yet even these creatures age and die. Where are the immortal salamanders
> or frogs?
>
Just out of interest, the limbs of regenerating amphibians are derived
from a specialised group of cells called the blastema, which form after
injury. Blastemal cells can be grown in culture indefinitely (and so, by a
cell biological definition are operationally immortal), yet these cells
can be marked and grafted back into a regenerating limb, where they take
part in forming the regenerate. Rather like embryonic stem cells (ES
cells) in mice.
Andy
--
Andy Groves
Division of Biology, 216-76
California Institute of Technology
