Ronald M. Green, an ethicist at Dartmouth College and an adviser to Advanced Cell Technology, said he hoped the new method “provides a way of ending the impasse about federal funding for this research.”

He said he believed the method should be seen as compatible with the Dickey-Wicker amendment, the Congressional action that blocked the use of federal funds for research in which a human embryo is destroyed or exposed to undue risk.

Dr. James Battey, head of the stem cell task force at the National Institutes of Health, said it was not immediately clear if the new method would be compatible with the Congressional restriction, since removal of a blastomere subjects the embryo to some risk. But the embryos that are P.G.D.-tested seem to grow into babies as healthy as other babies born by in-vitro fertilization, Dr. Battey said.

President Bush allowed federal funding for research on human embryonic stem cells, provided they were established before August 9, 2001. Although that might seem to rule out any new cell lines derived from blastomeres, Dr. Battey said it was not clear if that would be the case, since the embryo is not destroyed, and that he would seek guidance on the point.

Critics, however, have a range of objections to the research. Catholic bishops, in particular, oppose both in-vitro fertilization and P.G.D. testing, and therefore still object to the research, even though the cells would be derived from an embryo that is brought to term.

Richard Doerflinger, deputy director for pro-life activities at the United States Conference of Catholic Bishops, said the church opposed in-vitro fertilization because of the high death rate of embryos in fertility clinics and because separating procreation from the act of love made the embryo seem “more a product of manufacture than a gift.”

Asked if he meant the parents of an in-vitro child would love it less, Mr. Doerflinger said he was referring to the clinic staff.