As Spanish researchers unveil new stem cell research, Dr Adam Rutherford talks to Professor of Regenerative Medicine Fiona Watt. They look back at the history of stem cell research and what the future holds for regenerative medicine. Last week's discussion on science practicals generated huge amounts of feedback. Some listeners consider school practicals the secret to their success, others remember nothing more than breaking test tubes and blowing things up. Professor Robin Millar researches the best ways to teach science practicals; we ask him to respond to some of the points you raised. We unveil the mystery of the phantom head. Not an 18-rated horror film, but a dentists' training tool. This week's Show Us Your Instrument comes from Newcastle University's School of Dental Sciences. And, where there's muck, there's brass. In Newcastle, they're looking to sewage as a renewable alternative energy supply. It's flushed down the drains, but Northumbrian Water have taken a 'waste not want not' approach to our biological effluent. They are going to great efforts to recover energy from sewage and pump it back into the National Grid.