With everything known about human anatomy, you would not expect doctors to discover a new part of the body today. But now researchers say they did just that: they found a network of fluid-filled spaces in tissue that had not been seen before.
These fluid-filled spaces were found in connective tissue throughout the body, including below the surface of the skin; Lining of the digestive tract, lungs and urinary tract; and surrounding muscles, according to a new study that lists the results published today (March 27) in the journal Scientific Reports.
Previously, researchers had thought that these tissue layers were a dense "wall" of collagen ̵
The researchers said these fluid-filled rooms had been missed for decades because they did not show up. The researchers prepared tissue samples for these slides, treated the samples with chemicals, cut them into thin slices and stained them to highlight the most important features this fixation process is over The researchers discovered these fluid-filled spaces by using a new imaging technique that allowed them to study living cells.
Problems at a microscopic level.
The researchers call this network of fluid-filled spaces an organ – the interstitium. However, this is an unofficial distinction; For a body part to officially become an organ, there should be consensus around the idea as more researchers study it, Theise said on Live Science. The presence of these fluid-filled spaces should also be confirmed by other groups, he added
Aside from the official name, the findings could have implications for a variety of areas of medicine, including cancer research, said Theise. For example, the findings seem to explain why cancerous tumors that invade this layer of tissue can spread to the lymph nodes. According to the researchers, this occurs because these fluid-filled spaces are a source of a fluid called a lymph that drains into the lymphatic system. (Lymph is a fluid that contains infection-fighting white blood cells.)
A new organ?
About 60 percent of the human body is water. About two thirds of this water is in the cells, the other third is outside the cells and is called an "interstitial" fluid. Although the researchers already knew there was fluid between the cells, the idea of a larger, interconnected interstitium-in which there are fluid-filled spaces in tissues-was described vaguely in the literature, says Theise. The new study, he said, extends the concept of interstitium by showing these structured, fluid-filled spaces within tissues, and is the first to define the interstitium as an organ in and of itself.
The new work is based on the use of a relatively new technology called "probe-based confocal laser endomicroscopy" or pCLE. This tool combines an endoscope with a laser and sensors that analyze reflected fluorescence patterns and give researchers a microscopic view of living tissue.
Already in 2015, two of the authors of the study – dr. David Carr-Locke and dr. Petros Benias, both of them at New York City's Mount Sinai-Beth Israel Medical Center at the time, used this technology when they saw something unusual while examining a patient's bile duct for cancer spread. They found a series of interconnected cavities in the tissue layer that, according to a study, did not correspond to any known anatomy. When a pathologist slipped out of this tissue, the cavities disappeared-a mystery that later emerged as a result of the slide-making process.
In the new study, researchers used pCLE for the first time in cancer patients undergoing treatment for removal of the pancreas and bile duct. The imaging technique actually showed the fluid-filled spaces in the connective tissue. When the tissue samples were removed from the body, they were quickly frozen, leaving the fluid-filled spaces open so that the researchers could see them under a microscope.
Later, the researchers saw these same fluid-filled spaces in other samples of connective tissue from other parts of the body, in people without cancer, said Theise. "The more fabric I saw, the more I realized it was everywhere," he said.
The researchers believe that the fluid-filled spaces could act as shock absorbers to protect the tissue during daily tasks, the researchers noted, which could provide a wealth of information about this fluid-filled space; The researchers "did not even know what they saw." In fact, the researchers plan a review of the scholarly literature "for all the things we know about [body part] but did not know we knew it," the thesis said.
The idea presented in the study seems to be "a completely new concept," Dr. Michael Nathanson, head of the Department of Digestive Diseases at the Yale University School of Medicine, participated in the study. "From the evidence they presented, it is quite possible that they are correct," Nathanson told Live Science.
Earlier, doctors had a somewhat nebulous understanding of interstitial space, Nathanson said. They knew it was a fluid room found outside the cells, but nobody had ever fully explained what that meant. The new study had "done a good job" to define it, he said.
The results are consistent with what Nathanson and colleagues observed in a 2011 study. At that time, Nathanson and colleagues observed a network of dark fibers, but they were unable to find out exactly what it was. "I was pleased they confirmed our impression that this network exists" and could define it, Nathanson said.
The new finding "lets us ask all sorts of questions that we did not even know we should ask before," Nathanson said. For example, this area could be altered in disease or play a role in disease control, he said.
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