title: Current obstacles.
authors: Nuffield Department of Surgery, University of Oxford, Oxford Radcliffe Hospitals, England.
authors: P J
authors: PJ
authors: Morris
mesh_terms: D000818:Animals; D004992:Ethics, Medical; D006801:Humans; D011323:Primates; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology; D015047:Zoonoses / Q000635:transmission