The German parliament is set for a historic vote on whether to allow stem cells to be imported for use in research.
Proposals
Outright ban on imports
Restricted import of some cells
Unrestricted imports
Deputies will choose between three proposals which range from a total ban on the introduction of stem cells into Germany to allowing the unrestricted importation of them.
The vote is the culmination of two years of intensive debate between politicians, scientists and the church.
All research involving embryos is currently banned in Germany, where memories of the horrors perpetrated by Nazi scientists have made the issue particularly sensitive.
Industry and ethics
The party whip has been lifted for the vote but on Wednesday morning almost a quarter of deputies were still undecided about which proposal they would back.
It's not progress if we buy healing with the death of creatures who have the same value as we do
Cardinal Karl Lehmann
Chancellor Gerhard Schroeder urged the house to at least allow restricted imports in an address to the parliament prior to the vote.
"This is the only way we can have a say in how this research is used," he said.
"Otherwise, research won't stop but could go ahead following strictly economic interests and in places where ethical concerns have less force," he warned.
The Minister for Research, Edelgard Bulmahn, has also voiced her support for allowing the import of embryo stem cells under strict conditions.
"I am against an absolute ban on imports, as I am convinced that we would throw away opportunities, because we are not certain which methods will lead to the knowledge we need in biomedical research," she said.
A national ethics council, set up after a German institute applied to bring stem cells in from abroad, also recommended restricted imports in its report in November.
Supporters of imports warn that the German biotechnology industry risks losing important business if scientists go elsewhere to research on stem cells.
But others are concerned by the ethical implications of such research.
"It's not progress if we buy healing with the death of creatures who have the same value as we do," said Roman Catholic Cardinal Karl Lehmann.
Germany's president, Johannes Rau, has also warned that the development of gene technology risks reviving memories of atrocities and human experiments committed by the Nazis.