Inside the controversial world of animal testing: 'It's not putting lipstick on a kitten' - video

No animal industry attracts more criticism than research, where emotive images of lab rats, vivisection and cosmetic testing rub up against medical breakthroughs, genetic research and treatment for disease. The Guardian's Richard Sprenger visits three research labs to find out how the use of animals for research continues to evolve, and why the current conversation about sentience provides a bedrock for animal welfare