The surface area of the small intestine is increased by finger-like projections called villi.
The epithelium is a single layer of cells that are taller than they are wide. Where the section was cut orthogonal to the surface of the villi, a single row of cells is seen. Examine the structure of individual cells.
Surface Absorptive Cells (enterocytes) - their apical surface has tightly packed microvilli to increase their surface area. This is known as a brush border. The dark line underneath the brush border is the terminal web in which the microvilli are anchored.
Goblet Cells - scattered cells that secrete mucus. The secretion granules are clustered together near the apical surface. This is seen as a clear circular area due to the mucus being extracted during preparation of the specimen.