A communicating intestinal duplication in a Sprague-Dawley rat

Nonproliferative and Proliferative Lesions of the Gastrointestinal Tract, Pancreas and Salivary Glands of the Rat and Mouse

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) project is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature and diagnostic criteria for nonproliferative and proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and diagnostic criteria for classifying lesions in the digestive system including the salivary glands and the exocrine pancreas of laboratory rats and mice. Most lesions are illustrated by color photomicrographs. The standardized nomenclature, the diagnostic criteria, and the photomicrographs are also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and age related lesions as well as lesions induced by exposure to test items. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature and diagnostic criteria for the digestive system will decrease misunderstandings among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

A congenital ciliated epithelial cyst on the stomach of a B6C3F1 mouse

Congenital anomalies of the alimentary tract are rare lesions in laboratory animals. We describe a congenital cyst attached to the greater curvature of the forestomach in a B6C3F1 mouse. The inner surface of the cyst was mostly covered with cuboidal or pseudostratified ciliated epithelium and was focally covered with the flat cuboidal epithelium. The base of the cyst appeared to be inserted between the layers of the outer longitudinal muscle layer of the forestomach, although no smooth muscle layer was evident in the free surface of the cyst wall. The cyst resembled duplication of the alimentary tract, as it was lined with ciliated epithelium and had developed at the greater curvature of the forestomach. Since the smooth muscle layer did not completely cover the whole wall and the cyst did not communicate with the gastric lumen, the cyst was not thought to be a standard duplication but rather a simple congenital cyst.