Gastrointestinal system

The gastrointestinal system extends from the oral cavity to the anus and includes the intestines and associated glandular organs. The mouse has three paired major salivary glands, the largest of which is the submandibular gland, which is a prominent feature subcutaneously in the ventral neck. All the glands are composed of lobules and have a tubuloalveolar structure. The presence of digestive enzymes, bile, acid, digesta and commensal bacterial flora within the intestinal tract means that it is prone to rapid autolysis. Care should be taken to ensure that repeatable and consistent samples are taken from all animals as these organs are not homogeneous in their anatomy or function. The pancreas consists of three lobes splenic, duodenal and gastric which contain two major components, the exocrine secreting acinar tissue and the endocrine cells located in the islets of Langerhans.