When rats and dogs swallow a special kind of slippery molecule labeled with a tracking dye, the dye shows up in their skin, bones, and joints a day later—but a different tracking dye (technetium)...

When you give a big sugar-like molecule called hyaluronan to rats and dogs by mouth, it spreads through their bodies in a different way than a radioactive substance called technetium pertechnetate does.

When rats and dogs swallow a big molecule called hyaluronan, their bodies absorb it and it shows up in places like their joints, spine, and saliva glands—and it stays there for almost two days.

When rats were given a special version of hyaluronic acid by mouth, scientists found traces of it in their skin two days and four days later—and even more was in the skin than in the blood, which means the substance traveled through the body and reached the skin.