ILEUM - slide 131
What features identify this section as small intestine? In addition, identifying this specifically as ileum is the presence of a Peyer's patch (an aggregation of lymphatic nodules which lie mainly in the submucosa but also disrupt the muscularis mucosae and extend up into the mucosa). This slide has good goblet cells and a clear striated border on the surface epithelium. (Remember to equate the striated border with microvilli of electron microscopy.) Also the two layers of the muscularis mucosae are very clear here, and this is one of the best sections you have for both submucosal and myenteric autonomic plexuses.