Chapter 1 - Digestive Tract and Salivary Glands

Abstract

This chapter examines the gastrointestinal (GI) tract in the context of toxicologic pathology, including its role as a major barrier against systemic toxicity. Areas covered include normal structure and function, basic responses of the GI tract to toxicologic insult, and mechanisms of representative toxicants with GI-specific effects. Xenobiotics may cause disruption of GI mucosal barrier function, inflammation, ulceration, organ-specific immunogenic or neurologic dysfunction, changes to vascular perfusion, and altered cellular proliferation, including neoplasia. Tissue reparative responses include restitution, regeneration, and/or fibrosis. Complex interactions with the commensal gastrointestinal microbiome are necessary for maintenance of normal GI function and contribute to xenobiotic metabolism. Disruption of these microbial communities can have serious adverse consequences and complicate interpretation of toxicant effects. Other GI-specific toxicologic pathology topics include tissue preparation, molecular techniques, in vitro and in vivo laboratory methods, animal models, and a conceptual overview of regulatory and interpretive concerns.