Watch: This is why tattoos are permanent

Thank your immune system for those pretty stars on your neck that you love to show off.

If we shed about 40,000 skin cells per hour, how is it that tattoos don’t disappear after a few months? Why do they last ‘forever’?

The answer is not as straightforward as we would like it to be, but this TED-Ed video by educator Claudia Aguirre, director Hector Herrera and producer Pazit Cahlon, explains what happens in your body when the dye invades it.

When you get a tattoo, tiny needles loaded with ink will puncture your skin and penetrate both the epidermis—the outermost layer of skin—and the dermis—the inner skin layer, which contains blood vessels, hair follicles, glands, nerves and lymph vessels.

The wounds made by the needles cause inflammation, and the immune system quickly reacts by sending a type of white blood cells known as macrophages to heal the affected area. This process is what makes tattoos permanent.

Macrophages are ‘hungry’ cells that gobble on foreign material—in this case dye particles—to speed up the wound-healing process. Some of the macrophages that have 'eaten' the particles will go back to the lymph nodes, but others will stay in the dermis.

The rest of the dye will be soaked up by skin cells known as fibroblasts, and those, along with the macrophages, make your tattoo permanent.

And if you thought that the Chinese character you got tattooed in your most recent trip meant ‘peace’ and someone just recently pointed out that it actually means ‘kung pao chicken’, worry not—tattoos can be removed. Watch the video below to discover how it’s done.

https://www.youtube.com/watch?v=DMuBif1mJz0