Hugh Pickens writes "Nature reports that a paper reporting the creation of sperm-like cells from human embryonic stem cells has been retracted by the editor of the journal Stem Cells and Development. The journal's editor-in-chief Graham Parker says he took the radical step because two paragraphs in the introduction of the paper had been plagiarized from a 2007 review published in another journal. The retraction has surprised even critics of the paper, who had complained that the work had been over-hyped. "If there is nothing else behind this, it seems a little harsh," says Harry Moore, co-director of the Centre for Stem Cell Biology at the University of Sheffield, UK. The article reported that sperm precursor cells could be derived from human embryonic stem cells in vitro. These derived cells were able to divide and generate cells with just one set of chromosomes, characteristic of sperm. Although the text of the article modestly refers to these as "sperm-like cells" with "tail-like structures", its title, and the press release which accompanied its publication, refer baldly to human sperm. "That raised hackles," says Moore. "With that claim the authors opened themselves to criticism, some of it unfair, because the paper did not in fact show that sperm had been derived." Experts said Parker was right to retract the paper. "This is clearly scientific misconduct," said Allan Pacey, secretary for the British Fertility Society. "I can understand why people might think, if they were sloppy here, maybe they were sloppy elsewhere.""