Follicles are specialised collections of cells that produce the keratin filaments which we call hair. The follicles are not continuously active and have three growth phases which vary in length depending upon where on the body surface they are. These three phases are the anagen phase, when the follicle is actively producing a hair, a catagen phase during which growth stops and the hair falls out, and a thelogen phase when the follicle rests before recommencing growth.
The relative lengths of these phases can alter depending upon the role of the follicle, and this governs the ultimate length of the resulting hair. So a pubic hair has an anagen phase lasting a few weeks, and eyelash a week or so and a head-hair several years.
Part of this behaviour is genetically hard-wired into the follicle, but some is also under hormonal or metabolic control. Malnutrition, low protein intake and decreased thyroxine levels, for instance, which contribute to a reduced metabolic rate can contribute to reduced hair growth and hair thinning.
or maybe cause mini sean threatens the hairs if they start getting longer than him
why is ky yours and mine sooo damn awesome?
