Traditionally, confirmation of Transmissible Sponglform Encephalopathy (TSE) disease in humans or animals is by conventional light microscopy of stained tissue sections prepared from specific sites of formalin-fixed tissue after embedding in paraffin wax. This is the statutory method of confirmation of Bovine Spongiform Encephalphathy (BSE) in the United Kingdom and it is also used in other Member States of the European Community. However, two additional diagnostic criteria for TSE, the detection of disease-specific fibrils by transmission electron microscopy and the detection of the main constituent of the fibrils, an abnormal protein by immunoblotting, have also been reported. The former is the current method of confirmation for the statutory diagnosis of scrapie in the United Kingdom.