Examine the mucosa of the pyloric stomach (Fig. 15-19),

• Note that the pyloric glands, unlike the gastric glands found in the fundus and body of the stomach, contain mainly mucus-secreting cells and few parietal cells.
• Plus a few scattered gastrin cells representing the diffuse endocrine system along the gut.
• Cells of the enteroendocrine system will be considered more fully in a later topic, but they are not well-shown in routinely stained slides.

Compare and contrast the pyloric glands with the gastric glands.

Small Intestine -- site where digestion is completed, using enzymes from the pancreas and bile, and where products of digestion are absorbed. The three regions (duodenum, jejunum, and ileum, are similar histologically.) Examine the plastinated segment of small intestine, noting the features of its wall and mucosal folds.

Two sections of the duodenum (slides 4, 50), one section of jejunum (slide 158), and two of ileum (slides 21, 37) should be studied.

• On slides 4, 21, and 158, identify the major layers of the small intestine and the tightly packed together villi formed as projections of the mucosa layer (Figs. 15-25 through 15-35).
• Plicae circulares, large folds of the mucosa and submucosa (Fig. 15-26), are visible on slides 37 and 50, but are best shown on slide 158.

What is the difference between a villus and a plica circulares?

Brunner who?