Scientists May Have Just Discovered a New Organ—And It Could Be the Biggest Yet


A new study published in Scientific Reports boldly proclaims that researchers from NYU School of Medicine and Mount Sinai Beth Israel Medical Center, both in New York City, have identified a new organ in the body, thought to be the biggest organ of them all. Called "the interstitium," what has long been thought to be merely tough, dense connective tissue running throughout the body—beneath the skin, the visceral organs, around arteries and veins, and in the fascia tissue between muscles—is really a network of fluid-filled compartments whose structure easily defies viewing by traditional methods, the researchers say.

When asked how researchers can call something found in numerous parts of the body an organ, Neil Theise, co-author of the study, and professor of pathology at NYU School of Medicine, tells Mental Floss that it satisfied both definitions of an organ, being "a tissue that is unitary in structure" that has "a unitary set of functions." It might more accurately be called "an organ system" similar to the cardiovascular system and the lymphatic system.

In all of the places that it's found, the interstitium's fluid-filled compartments (which are the source of lymph, a fluid central to immune cell function) are surrounded by bundles of collagen and elastin—strong and flexible connective tissues that seem to form a sturdy framework for the compartments.

They have the "same cell types, same sort of structure [and] architecture, and the same relationship with the lymphatic system wherever they're found," Theise says. This makes sense, because the compartments drain directly into the lymphatic system. This might explain why cancer cells that get into the lymph nodes spread so rapidly.

This connection to the lymphatic system is also interesting because the last time scientists discovered a new part of the body, it too was connected to the lymphatic system: a system of vessels called the "central nervous system lymphatic vessels," which drain lymphatic fluid from the brain to the surrounding lymph nodes.

They believe the interstitium compartments act as a shock absorber that protects organs from tearing as they squeeze and pump during their daily functions. Moreover, since collagen bundles in lab settings are shown to generate electrical current, they suspect the same thing is happening within the compartments as organs and muscles bend and move. Theise thinks this might account for some of the responses people have to alternative medical treatments like acupuncture and myofascial release, which involves applying sustained pressure to myofascial connective tissue to relieve pain.


Prior to this study, Theise says, the literature describing this interstitial space—often called "the third space" after the cardiovascular and lymphatic systems—has been vague. Part of the problem is that the structure of the interstitium can't be viewed when it's flat—and that's generally how it's been seen. When scientists prepare tissue to put onto slides for viewing under a microscope, they use chemicals to remove the fluids from it, and slice it thinly, causing the normally fluid-filled interstitial compartments to collapse.

Researchers had noticed "cracks" between collagen fibers in fixed slides, but, Theise says, they were always told these were just "artifacts of having torn the tissue."

However, in the fall of 2015, researchers from Mount Sinai Beth Israel Medical Center discovered the true shape of the interstitium by accident when testing out a new technology called probe-based confocal laser endomicroscopy, which offers a microscopic view of living tissue. In this procedure, a thin, camera-bearing probe called an endoscope is snaked down a patient's throat, where scientists can view the insides of organs with a laser that lights the tissues, and a sensor that analyzes the reflected light. There, while scoping a patient's bile ducts, the researchers, who are co-authors on the current paper, saw something they'd never seen before: the interconnected, fluid-filled compartments.

The discovery opens numerous avenues for research. Theise's team will most immediately use the research to look at a rare liver disease they now think may begin inside the interstitial compartments. Next, they'll be gathering all the bits and pieces of information they have on the interstitium for a comprehensive literature review, Theise says, "organ by organ, cell by cell, and disease by disease."

10 Facts About Your Tonsils


Most of us only become aware of our tonsils if they become swollen or infected. But these masses of lymphatic tissue in the mouth and throat are important immunological gatekeepers at the start of the airways and digestive tract, grabbing pathogens and warding off diseases before they reach the rest of your body. Here are some essential answers about these often-overlooked tissues—like what to do when your tonsils are swollen, and whether you should get your tonsils removed.

1. People actually have four kinds of tonsils.

The term tonsils usually refers to your palatine tonsils, the ones that can be seen at the back of your throat. But tonsillar tissue also includes the lingual tonsil (located in the base of the tongue), tubal tonsils, and the adenoid tonsil (often just called adenoids). "Collectively, these are referred to as Waldeyer's ring," says Raja Seethala, the director of head and neck pathology at the University of Pittsburgh Medical Center and a member of the College of American Pathologists Cancer Committee.

2. Tonsils are one of the body's first responders to pathogens.

The tonsils are a key barrier to inhaled or ingested pathogens that can cause infection or other harm, Seethala tells Mental Floss. "These pathogens bind to specialized immune cells in the lining—epithelium—to elicit an immune response in the lymphoid T and B cells of the tonsil," he says. Essentially, they help jumpstart your immune response.

3. Adenoid tonsils can obstruct breathing and cause facial deformities.

If the adenoid tonsils are swollen, they can block breathing and clog up your sinus drainage, which can cause sinus and ear infections. If adenoids are too big, it forces a person to breathe through their mouth. In children, frequent mouth breathing has the potential to cause facial deformities by stressing developing facial bones. "If the tonsils are too large and cause airway obstruction, snoring, or obstructive sleep apnea, then removal is important," says Donald Levine, an ear, nose, and throat specialist in Nyack, New York. Fortunately, the adenoids tend to get smaller naturally in adulthood.

4. As many of us know, sometimes tonsils are removed.

Even though your tonsils are part of your immune system, Levine tells Mental Floss, "when they become obstructive or chronically infected, then they need to be removed." The rest of your immune system steps in to handle further attacks by pathogens. Another reason to remove tonsils besides size, Levine says, is "chronic tonsillitis due to the failure of the immune system to remove residual bacteria from the tonsils, despite multiple antibiotic therapies."

5. Tonsillectomies have been performed for thousands of years ...

Tonsil removal is believed to have been a phenomenon for three millennia. The procedure is found in ancient Ayurvedic texts, says Seethala, "making it one of the older documented surgical procedures." But though the scientific understanding of the surgery has changed dramatically since then, "the benefits versus harm of tonsillectomy have been continually debated over the centuries," he says.

6. ... and they were probably quite painful.

The first known reported case of tonsillectomy surgery, according to a 2006 paper in Otorhinolaryngology, is by Cornélio Celsus, a Roman "encylopaediest" and dabbler in medicine, who authored a medical encyclopedia titled Of Medicine in the 1st century BCE. Thanks to his work, we can surmise that a tonsillectomy probably was an agonizing procedure for the patient: "Celsus applied a mixture of vinegar and milk in the surgical specimen to hemostasis [stanch bleeding] and also described his difficulty doing that due to lack of proper anesthesia."

7. Tonsil removal was performed for unlikely reasons.

The same paper reveals that among some of the more outlandish reasons for removing tonsils were conditions like "night enuresis (bed-wetting), convulsions, laryngeal stridor, hoarseness, chronic bronchitis, and asthma."

8. An early treatment for swollen tonsils included frog fat.

As early practitioners struggled to perfect techniques for removing tonsils effectively, another early physician, Aetius de Amida, recommended "ointment, oils, and corrosive formulas with frog fat to treat infections."

9. Modern tonsillectomy is much more sophisticated.

A common technique today for removing the tonsils, according to Levine, is a far cry from the painful early attempts. Under brief general anesthesia, Levine uses a process called coblation. "[It's] a kind of cold cautery, so there is almost no bleeding, less post operative pain, and quicker healing. You can return to normal activities 10 days later," Levine says.

10. Sexually-transmitted HPV can cause tonsil cancer.

The incidence of tonsillar cancers is increasing, according to Seethala. "Unlike other head and neck cancers, which are commonly associated with smoking and alcohol, tonsillar cancers are driven by high-risk human papillomavirus (HPV)," he says. "HPV-related tonsillar cancer can be considered sexually transmitted."

26 Amazing Facts About the Human Body

Mental Floss via YouTube
Mental Floss via YouTube

At some point in your life, you've probably wondered: What is belly button lint, anyway? The answer, according to Mental Floss editor-in-chief Erin McCarthy, is that it's "fibers that rub off of clothing over time." And hairy people are more prone to getting it for a very specific (and kind of gross-sounding) reason. A group of scientists who formed the Belly Button Biodiversity Project in 2011 have also discovered that there's a whole lot of bacteria going on in there.

In this week's all-new edition of The List Show, Erin is sharing 26 amazing facts about the human body, from your philtrum (the dent under your nose) to your feet. You can watch the full episode below.

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