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.

When mice experience sudden stress, it causes the cells that give hair its color to panic and leave their home in the hair follicle, burning out too soon and making the fur turn gray forever.

When the stem cells that give your hair its color get worn out or change too early because of stress in the cells, they stop making pigment, and your hair turns gray permanently.

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.