A prion is an infectious agent, componed entirely o protein, presumed tae be the cause o the transmissible spongiform encephalopathies (TSEs).

Prion Diseases (TSEs)
Histology bse.jpg
Microscopic "holes" are characteristic in prion-affected tissue sections, causin the tissue tae develop a "spongy" airchitectur.
Clessification an freemit resoorces
ICD-10A81
ICD-9-CM046