31.   Because stem cell research fiddles with human embryos, however, anti-abortion forces oppose it.

32.   Because cloning involves experimenting with human embryos, it raises fundamental questions of when human life begins, questions that lawmakers have wrestled with for nearly a year.

33.   Because the research, which uses human embryos discarded from fertility clinics, has become enmeshed in the politics of abortion.

34.   Biologists supported by Geron have developed embryonic stem cells, derived from human embryos or fetuses, and these could in principle generate every tissue of the body.

35.   -- Turned away a court challenge to medical research on human embryos.

36.   A battle is raging within the Bush administration over whether to prohibit federal support for biomedical research that uses cells derived from human embryos, federal officials say.

37.   A biotechnology company announced Sunday that it had taken the first steps in producing cloned human embryos for use in growing replacement cells to treat diseases like diabetes.

38.   A great deal of research must be done, in animal cells and in those derived from human embryos.

39.   A Massachusetts biotechnology company, Advanced Cell Technology, provoked a storm of outrage last month by reporting that it was trying to create human embryos by cloning.

40.   A petri dish containing human embryos is examined at the Montefiore Fertility Clinic in Dobbs Ferry.