National Bioethics Advisory Commission employs the distinction as introduced by
Harold Varmus, then NIH director, at a hearing in January 1999. Totipotent cells have "unlimited
capacity. Totipotent cells have the capacity to differentiate into the embryo
and into extra-embryonic membranes and tissues. Pluripotent cells "can generate all of the cell types
in a fetus and in the adult that are capable of self-renewal. Pluripotent cells
are not capable of developing into an entire organism." Ethical Issues in Human Stem Cell Research
(September 1999) by NBAC, 6100 Executive Boulevard, Suite 5B01, Rockville,
Maryland 20892-7508; www.bioethics.gov.
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