Schematic drawing of the characteristic histologic changes seen in celiac disease as described by Marsh. The lesions range in severity from only increased numbers of intraepithelial lymphocytes in the early stages (Type I) to elongation of the crypts (Type II) and progressive villus atrophy (Type 3a to 3c).
IEL: intraepithelial lymphocytes; EC: epithelial cells (in villus).
Modified from: Marsh MN. Gluten, major histocompatibility complex, and the small intestine. A molecular and immunobiologic approach to the spectrum of gluten sensitivity ('celiac sprue'). Gastroenterology 1992; 102:330.