Newfound Human Organ Holds a 5th of Body's Fluid

A pathologist investigating strange patterns spotted in routine endoscopies found a previously undiscovered human organ lurking right inside his nose. The interstitium, a network of fluid-filled spaces, is found in tissues throughout the body, including below the surface of the skin and surrounding the digestive tract. The organ, described by Time as a "bubble wrap-like network," was detected with the help of modern laser endoscopes that allow researchers to analyze living tissue at a microscopic level. Previously, tissue samples were treated and put on slides before microscopic analysis, a process that caused fluids to drain away, collapsing the interstitium and making the samples seem like they were from a hard wall of connective tissue.

In a study published in Scientific Reports, pathologist Neal Theise and colleagues describe what they say is a "previously unrecognized, though widespread, macroscopic, fluid-filled space within and between tissues." Theise, who used an endomicroscope to detect the network under the skin of his own nose after he was consulted about the patterns seen in endoscopies, says the interstitium contains about a fifth of the body's fluids. He says it seems to act as a "shock absorber," but may also help cancer cells spread to the lymphatic system, the New Scientist reports. "Once they get in, it's like they're on a water slide," he says. "We have a new window on the mechanism of tumour spread." (Last year, the mesentery was identified as the body's 79th known organ.)