91.   The rules permit federally financed researchers to use cell lines that are derived from frozen human embryos due to be discarded by fertility clinics.

92.   This was the main reason President Bush limited research financing to work on existing cell lines, a small number that many scientists believe is insufficient.

93.   They turn on the enzyme telomerase, and this makes the cell lines immortal.

94.   Those five cell lines alone comprise a main source of raw material being used now, at least in the United States.

95.   To realize the full promise of stem cells, scientists say they will need to develop cell lines that are immunologically compatible with patients.

96.   To ease those qualms, Bush decided to confine federal financing to work involving cell lines that were already established at the time of his speech.

97.   Under the new Bush plan, a registry of the self-renewing cell lines already in existence will be created at the National Institutes of Health.

98.   Until it does so, scientists will be uncertain whether there will be enough cell lines of sufficient quality and whether they will be available without excessive restrictions.

99.   Under his plan, taxpayer money may be used to study only those cell lines that already exist.

100.   Varmus denied that by funding research on the existing cell lines, the government will be encouraging their creation.