A potentially game-changing medical breakthrough has altered the way scientists understand the human body, and it all has to do with a flap of abdominal membrane lining first discovered by Leonardo di Vinci in 1508.

Largely ignored for centuries, scientists previously believed the structure — known as the mesentery — was actually a series of unconnected structures holding our digestive organs in place. However, two scientists in the United Kingdom recently discovered the mesentery is in fact one continuous structure, a finding that could have big implications for medical science.

The new analysis, published in The Lancet Gastroenterology & Hepatology by Professor J. Calvin Coffey and Dr. Peter O’Leary, has caused the structure to be recategorized as an organ, which will create more opportunities for holistic study of the mesentery’s role in abdominal diseases. Before the discovery, scientists had believed the human body contained only 78 organs.

“We now need to reinterpret intestinal anatomy, and indeed other areas of anatomy, in light of the new model,” Coffey, who is also a surgeon, told ATTN:.

The transformation of the mesentery has already prompted an update to Gray’s Anatomy, one of the world’s most well-known medical textbooks.

Coffer told ATTN: he believes the discovery will help “enormously” in understanding various diseases, but before he could elaborate he had to go perform a surgery.

We will update this post once we learn more.