GASTRO-DUODENAL JUNCTION - slide 126 (dog)
The histological transition from stomach to duodenum is likely to take place in a highly folded region of the wall, making the section inevitably tangential in relation to glands and other features. Start (with low power) at the clearly pyloric end of the section, where you can see the typically coiled mucosal glands lying above the muscularis mucosae. Then follow along the mucosa, through a tangentially cut, rather mixed-up area, until the layers sort themselves out clearly again and you can see the submucosal gland of Brunner lying below the muscularis mucosae. At about this point you should also find crypts of Lieberkuhn (mucosal intestinal glands) and you should also see goblet cells in the crypt linings. In this section, the villi are rather stubby and denuded of their epithelial surface, leaving only a core of lamina propria. Such loss of cell integrity is a common postmortem phenomenon among populations of highly active, metabolically sensitive cells. Notice solitary lymph nodules scattered in the submucosa and/or lamina propria throughout the section.