Mouse hair pigment cells move between different parts of the hair follicle and change their state back and forth, which is linked to WNT signaling.

WNT signals in the hair follicle are linked to pigment cells turning into mature color-producing cells in mice.

Skin cells around the hair follicle make WNT signals that turn on WNT activity in pigment stem cells in mice.

When mouse hair starts growing, pigment stem cells in the hair germ turn on color-making and branch-related genes before they divide.

When mouse hair is repeatedly plucked, more pigment cells get stuck in the bulge area (from 10% to 50% of follicles), and these stuck cells don't help make new hair color.

Your hair color depends on special stem cells in your hair roots, and long-term stress from inflammation or oxidation can mess them up, making them disappear or mature too soon.