51.   But the government does not have control over whether those cell lines get to researchers, according to Gulbrandsen, federal health officials and patent law experts.

52.   But the number of cell lines is certain to spark debate.

53.   California-based Geron may be the leading owner of cell lines in the United States with six, though only three are thought to be usable for experiments.

54.   Cell lines are easily contaminated, and finicky.

55.   Cell lines derived from fetal tissue provide a medium for growing viruses used in vaccines.

56.   Eventually, everyone agreed the evidence was sufficient, since two different cell lines in two different laboratories were now significantly beyond their usual number of divisions.

57.   For basic immunological studies they wanted to produce long-lived laboratory cell lines that would make antibodies of a known and easily identifiable kind.

58.   For such implants to become widespread, however, researchers must develop a cell line that can be cultured in the lab and produced in large quantities.

59.   He noted that the cell lines cannot possibly become human beings.