Susan Standring has been the editor in chief of the 39th, 40th and 41st editions of Gray’s Anatomy, the venerable tome on the human body. She is now at work on the 42nd. “Hippocrates said that anatomy is the basic discourse of medicine,” she says, “and like any medical discourse, it is ongoing.”

It may seem curious that something as well studied as the body should harbor uncharted territory. Yet every age has managed to make discoveries, Standring says. In the sixteenth century, which she describes as “the Golden Age of anatomy,” anatomists at the University of Padua in Italy corrected errors in anatomical texts that had been used for centuries.

In 1784 the German writer Goethe announced that he had found a previously unknown bone in the jaw—the intermaxillary—though two others, a few years earlier, had each discovered it independently. The passage of the Anatomy Act of 1832 eased restrictions on human dissection in the United Kingdom, opening the doors to further progress in clinical medicine, such as the first imprint of Gray’s Anatomy in 1858.

The latest discoveries come as the result of advances in technology, Standring says. Robotic and laparoscopic surgery, for instance, allow surgeons to explore parts of the body that had previously been difficult to access in living subjects. And advances in medical imaging—which resulted in three of the five discoveries to the right—allow researchers to see living tissues in high resolution. “The recent progress has been extraordinary,” she says, “and I don’t see an end in sight.”

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Art by Getty Images (figure); Inset images from Gray’s Anatomy 1918 edition; Jill Gregory (Interstitium), printed with permission from mount Sinai Health System, licensed under CC-BY-NC-ND.