Researchers have engineered artificial penises in rabbits, using cells from the animals, who then used their new organs to father baby rabbits.The work takes scientists closer to making other complex solid organs such as livers using a patient's own cells, the researchers reported in the Proceedings of the National Academy of Sciences on Monday. It provides a tailor-made transplant, said Dr. Anthony Atala of Wake Forest University Baptist Medical Center's Institute for Regenerative Medicine, who led the study.