Intestinal Fortitude
We rarely see the cells that help defend us from the microorganisms and debris that can cause sickness. Visible as white spots in the interior of these intestinal villi, however, are immune cells called macrophages, which do just that. Macrophages engulf microorganisms like bacteria and viruses that can cause illness and also help clean up microscopic debris that, if left unchecked, could accumulate and cause damage.
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We rarely see the cells that help defend us from the microorganisms and debris that can cause sickness. Visible as white spots in the interior of these intestinal villi, however, are immune cells called macrophages, which do just that. Macrophages engulf microorganisms like bacteria and viruses that can cause illness and also help clean up microscopic debris that, if left unchecked, could accumulate and cause damage.
What am I looking at?
This image shows a cross section through several villi in the small intestine of a mouse. The yellow lines around the exterior of each villus are its brush border (1). The purple lines just inside the yellow are the cell membranes of some of the cells that compose the villi (2). The blue ovals are the nuclei of those cells (3). The white spots on the interior of the villi are the macrophages (4).
Biology in the background
All the food and drink that we consume passes through our small intestine. However, food and drink are rarely sterile, which means we also consume microorganisms like bacteria and viruses that can sometimes cause illness. Fortunately, there are immune cells throughout the digestive tract, including in the small intestine, which help protect us from these foreign organisms. One of these immune cells is the macrophage, which recognizes, engulfs, and destroys pathogens and other harmful particles. Macrophages are mobile and move throughout the body, cleaning up the debris that we accidentally but inevitably bring into our bodies.
A macrophage is about 20 micrometers across, or roughly four times smaller than the width of a human hair.
Technique
This image was produced using fluorescence microscopy.
Kristen Engevik, Baylor College of Medicine