How do tattoos and scars stay permanent?

-Karthik Gurumurthy

Most people ask this question about how they stay permanent if the cells of our skin are replaced regularly.

Our skin is mainly made of a protein called collagen, which is produced by cells known as fibroblasts. When the skin (or tissue) gets wounded, the wound-healing proces initiates the generation of new fibroblasts to produce scar collagen which is different from the collagen in normal skin. Even though individual cells within the skin periodically die and are replaced with new cells, the scar collagen stays. The only time when wounds will heal without producing scars is during fetal stage of life, when the skin produces fetal collagen, a protein that is different from adult collagen. If we could find a way to turn on the production of fetal collagen after birth, then we would perform scarless surgery.

Tattoos remain in the skin because the ink particles that produce the coloration are too large to be ingested by the WBCs (White Blood Cells) that patrol the body and carry foreign bodies away from the skin. The new tattoo removing lasers, what they do is, the laser energy crush the ink into microfine dust particles that are small enough to be taken in by the WBCs and carried away.