WELL BEFORE BIRTH




Isolated dermal papilla
Knowledge about hair generation comes from the greater understanding we now have of the communication between the cells responsible for regulating its formation.



A hair is formed within the hair follicle. The real question is therefore to know how this follicle is formed.


This starts during the third month of embryonic life. Between the epithelial tissue - or epithelium - which will form the epidermis of the skin and the connective tissue which will become the dermis, numerous messages begin to be exchanged.
This genuine interactive conversation produces two simultaneous phenomena. In the basal layer of the epithelial tissue, in contact with the connective tissue, some cells multiply and create a bud-like structure. Under this bud, connective cells clump together; these cells will be the origin of the dermal papilla and the connective tissue sheath.

The epithelial bud pushes down into the connective tissue. On this epithelial column, two bulges appear: one will become the sebaceous gland, while the other will be the point at which the arrector muscle will be inserted.

This column meets the dermal papilla and attaches itself to it as if it were a press-stud, i.e. by almost entirely surrounding it, itself being enclosed within the connective tissue sheath which has developed from the base of the papilla.
This union between the epithelial component and the dermal component marks the true birth of the hair follicle. It can thus be clearly seen that the follicle is an epidermal cavity within the dermis .

It is at this stage that the construction of the hair really begins. The papilla becomes the real driving force of the follicle. Under its direction, the cells situated in the deeper part of the epithelial component, the matrix, multiply very rapidly by mitosis and differentiate. Some form the external and internal epithelial sheaths of the follicle. Others form the hair shaft. Unable to develop downwards, these cells will move upwards and the hair shaft will pierce the superficial layer of the epidermis, making the hair finally visible.

A surprising and essential fact, unique to hair, is that throughout life, it is these same embryonic processes which will continue to occur producing the growth cycle of hair.

By considering both hair on the head and hair on our skin, which despite their many differencesare formed from comparable hair follicles, the following chronology of embryonic life can be established:


- Towards the end of the second month and during the third, the construction of hair follicles begins in the region of the eyebrows, the chin and the upper lip.

- From the fourth month, the process spreads progressively from the head towards the lower part of the body. At birth, all the hair follicles of the body are in place.

- As they are formed, the hair follicles at first produce a fine short colourless hair: the lanugo.

- Between the seventh month of embryonic life and the first days of extra-uterine life, the lanugo disappears.

- This lanugo is replaced by a slightly thicker and longer hair: vellus hair . It is only at puberty that body hair will be replaced by the definitive hair.

- As far as hair on the head is concerned, it directly replaces the lanugo from the seventh month.





WELCOME
PORTRAIT OF AN UNKNOW ELEMENT

WHAT WE DON'T SEE : THE ROOT

WHAT WE DO SEE : THE SHAFT

SUPERB CHEMISTRY

WELL BEFORE BIRTH
LIVING AND RELIVING
AMAZINGLY NATURAL
SO STURDY AND YET SO FRAGILE
INFINITE TRANSFORMATIONS
THE HAIR A SCIENTIFIQUE ENIGMA
HAIR AND CULTURE
EXHIBITIONS
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