If all works correctly, a monoclonal cell colony will be produced.

Indeed, they said it seemed that as few as two cell colonies had been used to generate photographs.

In the photo, the embryonic stem cell colonies are the rounded, dense masses of cells.

Counting the cell colonies is usually done under a microscope and is quite tedious.

The critics then showed that several of the photographs overlapped, even though they were supposed to be of different cell colonies.

The identical photograph, a test of pig embryonic cell colonies, seemed to have been presented twice but as representing different cells.

Heterogeneity in proliferative potential of ovine mesenchymal stem cell colonies.

The development of a biofilm may allow for an aggregate cell colony (or colonies) to be increasingly antibiotic resistant.

The National Institutes of Health says there are 78 self-sustaining cell colonies, called lines, that researchers may work on.

Brú's theory stems from his mathematical research on the Fractal growth of tumour cell colonies in vitro.

These services allow scientists to identify genetic abnormalities in cells or changes in stem cell colonies that might affect research results.

The journal's referees were sent the original submission, so they could not have spotted the duplicate cell colony photos that were later published.

Roh was one of the co-authors of the article that detailed how individual stem cell colonies were created for 11 patients through cloning.

The cells were cultured in the continuous presence of G418 (200 g/ml) for approximately 2 weeks, and the resulting total cell colonies were harvested.

The test, demanded by referees for Science, was necessary because cell colonies often get mixed up or overgrown by other cells in even the best laboratories.

Their accusations, posted anonymously on Korean Web sites, first showed that some of the photographs of the 11 cell colonies were duplicates.

The critics also noticed a strange feature in the DNA fingerprints taken of the cell colonies and the donors from whom they were supposedly derived.

Dr. Hwang claimed yesterday that he had succeeded in making embryonic cell colonies from some patients, but that the cells were killed by a fungus.

One would encourage the National Institutes of Health to finance alternatives to develop embryonic stem cell colonies without destroying embryos.

With a ready source of cells, Dr. Puck performed groundbreaking experiments, exposing the cell colonies to different levels of radiation.

Currently, federal money can be used for research on only a limited number of existing embryonic stem cell colonies, or lines, that were created before Aug. 9, 2001.

The president, echoing the anti-abortion lobby, decreed in August 2001 that federally financed research be tightly limited to the embryonic stem cell colonies that existed then.

The newest questions about the paper concern DNA fingerprint tests carried out to prove that the embryonic stem cell colonies were indeed derived from the patient in question.

Mr. Bush has stood by his decision, announced in 2001, to allow the federal government to pay for research on a limited number of existing embryonic stem cell colonies, or lines.

What Mr. Bush permitted was federal money for research only on the relatively small number of stem cell colonies that existed in August 2001 when his policy was announced.