A routine endoscopy—a procedure that involves inserting a camera into a person’s intestinal tract—may have led to the discovery of a previously unknown human organ. One team performing an endoscopy expected to find a certain type of tissue surrounding the bile ducts, which are sort of like drainage pipes that carry bile from the liver to the gallbladder and from the gallbladder to the small intestine. Neil Theise, a pathologist at New York University School of Medicine, looked at their findings.

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Here’s Jessica Hamzelou, reporting for New Scientist:

When Theise used the same endomicroscopy device to look under the skin of his own nose, he saw a similar result. Further investigation of other organs suggested that these patterns are made by a type of fluid moving through channels that are everywhere in the body. Theise reckons that every tissue in the body may be surrounded by a network of these channels, which essentially form an organ. The team estimate that the organ contains around a fifth of the total fluid volume of the human body. “We think they act as shock absorbers,” says Theise.

This is probably the first time we’ve seen this organ because most of the time when experts visualize human tissue, the practices they use cause these channels to drain. The collagen fibers that act as the network’s “skeleton” collapse, too. So in the past, scientists would have seen these channels camouflaged as hard, dense tissue. More advanced procedures, like the one this team used, are allowing this network to come into view. Theise also found that cancer cells can make their way into these channels, leading them directly to the lymphatic system. This means that diving more deeply into the structure and function of this new human organ could help identify and diagnose cancer at an earlier stage.

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Image credit: National Cancer Institute / Georgetown Lombardi Comprehensive Cancer Center