Scientists have finally closed the case on how fingerprints form.
Fingerprints are the looping, swirling stripes on the tips of your fingers. These raised ridges of skin develop before birth. They were known to expand out from three spots on each fingertip: under the nail, in the center of the finger pad and the crease of the joint closest to the tip. But no one knew what determined a fingerprint’s final pattern.
Now, scientists have found that three interacting molecules cause fingerprint ridges to form their signature stripes. The way those ridges spread from their starting points — and then merge — determines the overarching shape of a fingerprint.
Researchers described the work March 2 in Cell.
Unmasking the molecules behind fingerprints
Each person’s fingerprints are unique and last a lifetime. They have been used to identify individuals since the 1800s. But fingerprints are not just good for solving crimes. These ridges help humans and many animals that climb — such as koalas — hold onto objects and distinguish textures.
Scientists knew that fingerprint ridges start to form by growing down into the skin, like tiny trenches. Cells at the bottoms of the trenches quickly multiply, going deeper. But a few weeks later, the cells stop growing downward. Instead, they continue multiplying but push the skin upward, creating thickened bands of skin.
To find out what molecules might be involved in this growth, researchers turned to another skin structure that grows downward: a hair follicle. The team compared skin cells from developing hair follicles to those in budding fingerprint ridges. Molecules found in both places, the scientists figured, could be responsible for downward growth.
Both structures shared some types of signaling molecules. These chemical messengers pass information between cells. Both budding hair follicles and fingerprint ridges had molecules called WNT, EDAR and BMP.
Further experiments showed that…
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