An Intestinal Mosaic

What am I looking at?

This image shows a horizontal cross section through several villi (imagine that their tops have been sliced off and you’re looking down into them) in the small intestine of a mouse. The outer membranes of the intestinal villi are the solid-colored lines (1). The cells within the villi are the multicolored imperfect circles (2).

Click on the right arrow to see a cross section through a different intestinal sample.

Biology in the background

The small intestine – in mice and humans alike – plays an important role in digesting the food we eat and absorbing nutrients into the bloodstream to be distributed to the rest of the body. Nutrients are absorbed through a membrane on the surface of the interior wall of the intestine. This wall is lined with villi to increase the surface area of the membrane that absorbs nutrients.

Within each villus are four main types of cells: enterocytes, which are by far the most numerous and are primarily involved in absorbing nutrients from inside the intestine; goblet cells, which secrete mucus to create the lining of the intestine; enteroendocrine cells, which secrete molecules that aid in the digestion and absorption of nutrients in the small intestine; and tuft cells, which work with the immune system to defend against pathogens. All these cells work together to keep the intestine healthy and functioning properly.

In a human, a villus averages about 50 micrometers to 70 micrometers thick, or slightly smaller than the width of a human hair.

Technique

These images were created using fluorescence microscopy.