Art of Hair Micro Grafting:
The "Good and the Bad Hair"

Without going into scientific details, it is interesting to understand why, at the man, the hair of the top of cranium fall, whereas the hair of the crown persist.

This phenomenon finds an explanation in the fact that the hair of the crown has a particular genetic specificity, different from the hair of the top of the cranium (area of the vertex), which tends "to protect them" from the harmful action of the androgens.
This hair has one prolonged lifespan, unlike the hair of the top of the head, whose cycle of renewal accelerates and thus the lifespan is curtailed.

Let us retain that each one of our hair is renewed by cycle and that the normal cycle of a hair includes 3 distinct phases: 

1. a phase of growth.
2. a phase of stabilization.
3. a phase of ageing leading to cellular death.

In the normal case of a man or a woman not subjects to baldness, each dead hair is replaced by a new hair which, itself, enters a new cycle of growth and so on.

For the subject which loses his hair in a pathological way, the difference lies in the fact that his dead hair is not replaced.  Also, the repetition of this process over a more or less long period, transforms a beginning of hair loss into a more significant hair loss, until the appearance of  authentic baldnesses.

On average, each hair can undergo from 23 to 25 cycles of renewal on a whole life, knowing its longevity is genetically programmed, from two to four years at the man, from four to six years at the woman.

Baldness thus does not depend on such or such area on cranium, but it rather depends, according to their localization, on the presence of "weak or strong hair".