Scientists claim to have identified a new human organ, which was hiding in plain sight, in a discovery they hope could help them better understand the spread of cancer within the body.
Called the interstitium, this compartment is found everywhere throughout the body, beneath the skin, as well as lining the gut, lungs, blood vessels and muscles, and joins together to form a network supported by a mesh of strong, flexible proteins.
It surrounds arteries, muscles, and the digestive and urinary tracts, in a layer long thought to be dense connective tissue.
A recent report published in the journal Scientific Reports is the first to identify these spaces collectively as a new organ and to try to understand their function.
Remarkably, the interstitium had previously gone unnoticed despite being one of the largest organs in the human body.
Mount Sinai Beth Israel Medical Centre medics Dr David Carr-Locke and Dr Petros Benias came across the interstitium while investigating a patient's bile duct in the search for signs of cancer.
They noticed cavities that did not match previous knowledge of human anatomy, and approached New York University pathologist Dr Neil Theise to ask for his expertise.
The ground-breaking discovery of the new organ could help solve age old health mysteries and provide insights into the spread of cancer.