If every cell in our body is replaced about every 7 years, how is it that tatoos last a lifetime?

Question

Unless purposely removed, of course. What I'm getting at is how does the body replace the old ink-impregnated cells with new cells that are also ink-impregnated? Where does the body get the ink from, and how and why does it make an exact copy?

Answer 1

It would appear that the tattoo ink is a foreign substance between the cells and not necessarily within them. Just as a steel splinter or a bullet can remain lodged inside the body (while all the cells around it are being replaced) the ink can survive the passage of time. The ink must be deposited within a deeper layer of skin than the epidermis (the outer layer) because cells there are constantly forming a dead horny layer that washes or wears away.