1. Inflammatory Bowel Disease Study Group, University Department of Surgery, Pond Street, London NW32QG, UK
2. Department of Medicine, Royal Free Hospital and School of Medicine, Pond Street, London NW32QG, UK
3. Department of Anatomy, Royal Free Hospital and School of Medicine, Pond Street, London NW32QG, UK
4. Department of Histopathology, Royal Free Hospital and School of Medicine, Pond Street, London NW32QG, UK