An organ is a group of tissues that has a unique purpose. They perform vital life-supporting functions, like pumping blood or eliminating toxins.

Many resources state that there are 79 known organs in the human body. Together, these structures keep us alive and make us who we are.

But according to recent research, there may be even more organs in the body. This includes the interstitium, a structure that some experts think is the new biggest organ.


To date, the skin is considered to be the largest organ. It covers your whole body and makes up about 16 percent of your overall body mass. Your skin is approximately 2 millimeters thick.

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The function of your skin is to:

protect your body from environmental stressors like germs, pollution, radiation from the sun, and moreregulate your body temperaturereceive sensory informationstore water, fat, and vitamin D

But, according to a 2018 article, the interstitium may now be the largest organ. Their findings, which classify the interstitium as an organ, suggest that it might be bigger than the skin.


What is the interstitium?

More than half of your body’s fluid is located in your cells. About a seventh of your body’s fluid is found in the lymph nodes, lymph vessels, heart, and blood vessels. The rest of the fluid is called interstitial fluid.


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The interstitium is a series of fluid-filled spaces made of flexible connective tissue. This network of tissue is sometimes called a lattice or mesh.

It’s found in many parts of your body, including:

beneath your skin’s surfacein the lining of your lungs and digestive tractin the lining of your urinary systemsurrounding your arteries and veins

It’s well-established that the interstitium is the body’s main source of lymph fluid. However, the study’s authors believe it also protects tissue from the natural movement of your organs, like when your GI tract contracts while digesting food.

They say it may also have a role in conditions like cancer and inflammatory diseases.

Due to these findings, the authors say the interstitium’s unique function makes it an organ. But not all scientists agree.

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If the medical community decides it’s an organ, it would be the 80th and largest organ in the body.

Until the 2018 report, the interstitium hadn’t been extensively studied. More research is needed to fully understand the interstitium, as well as its function and overall size.