Intestinal epithelium

The single columnar epithelium of the small intestine consists of different epithelial cells. The palisade-like epithelial cells are tightly connected with cell junctions. The intestinal epithelium is folded into finger-like projections called the villi. Each villus contains blood and lymph vessels that efficiently distribute the nutrients that were absorbed by the cells of the intestinal lining. These are key targets for pathogens, therefore the intestinal lining is an important barrier that is well guarded by the immune system.

Three panels. Left most shows a 3D structure of villi with blood vessels at the bottom and lymphatic vessels penetrating each protrusion. The bottom where two villi intersect is labelled the gland or crypt of Lieberkuhn.
Middle panel shows a zoomed up view inside a protrusion. Small dark purple dots beneath the epithelial layer are labelled lymphocytes. A white area labelled lamina propria is found beneath the epithelium and extending almost to the tip of the protrusion. 
Panel three shows a zoom up of two adjacent epithelial cells. Below the cells are the capillaries and nerve endings. The cells have 5 different types of touch points. At the bottom are gap junctions which appear as tubes between the two cells. Above this, is a desmosome which is a thick junction with lots of thin stands leading into each cell. Above this is the adhesive belt which goes around the perimeter of the entire cell. Above this are the tight junctions which are close touch points between the two adjacent cells. Finally at the top are the microvilli of each cell.

Figure 1: Components of the intestinal epithelium: (1) villi, (2) lymphatic vessel, (3) blood vessels, (4) gland (crypt of Lieberkuhn), (5) epithelium , (6) lymphocytes, (7) lamina propria, (8) goblet cell, (9) microvilli, (10) tight junction, (11) adhesive belt, (12) desmosome, (13) gap junction, (14) nerve ending, (15) capillary.