CBS Local — Just like finding a long lost relative, scientists would like to introduce you to an organ you never knew you had: the interstitium.

New research published in Scientific Reports has revealed that the human body contains a network of fluid-filled channels that had previously been undiscovered. The spaces were found all around the body’s connective tissue which lines the digestive tract, lungs, urinary systems, and surrounding muscles.

While the fluid-carrying channels have not been officially designated an organ by a majority of scientists, Neil Theise of New York University’s School of Medicine says the interstitium holds nearly a fifth of the body’s fluids. “We think they act as shock absorbers,” Theise said, via New Scientist.

Theise and his team add that the interstitium may also explain how cancer cells spread from one area of the body to another. Scientists searching for reasons why cancer sometimes spreads to patient’s lymph nodes are looking at this fluid channel as the possible answer.

Lymph, a fluid containing illness-fighting white blood cells, drains into the human lymphatic system and the interstitium may be the source of this fluid transfer. “Once they get in, it’s like they’re on a water slide,” Theise claims. “We have a new window on the mechanism of tumor spread.”

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