Articles | 11-12-20

What determines the hair type?


I wonder about the hair follicles and what determines the characteristic of hair. If I move a hair follicle from my head to my arm. Will that hair grow on the arm in the same way it did on my head? Will the position on the body determine how much the hair follicle grows?


What controls our genes, that is, our DNA. All humans have about 25,000 genes in each DNA molecule in each cell throughout the body, except for germ cells that have their own DNA in the nucleus. Each cell and every gene contains an incredible amount of information. To give your hair cells their special properties, several different genes work together and this will shape your hair, affect your hair loss, your hair color and the shape of your hair.

What separates the appearance of the hairs in terms of shape, is the production in each hair follicle. There are essentially three different shapes – round openings that provide a straight hair, oval openings that give a wavy hair and very oblique openings that give a curly hair. There may be a mixture of the different openings on the same head, and the hair follicle openings may vary slightly, and this gives hair which can be smooth, but with a bit of wavy character.

The last question was about how the hair behaves when it transplants from one area to another. To describe it in an easy-to-use way, we take an example:  People who have thin eyebrows from birth, or has picked or shaved them away, or who for other reasons want to have thicker eyebrows, will have to do an eyebrow transplant.

It involves moving hair from part of the body to the eyebrows. On the body there is obviously no eyebrows’ hair to take off for a transplant. An eyebrow’s transplant differs from when we take hair from the neck and move it up to the scull during a regular hair transplant. We always take hair from the neck and insert into the eyebrows. This will look good, but the hairs will grow like neck hair, which means that the person will have to cut them continuously, so they will not hang down over the eyes. The hair is often a bit coarser in the neck compared to eyebrows’ hair, and some hair may start to grow a bit crooked, but then this hair must be picked away.

Over time, some hair may change, depending on the surroundings, but that is not a matter of course. For about 50 % of all people who get an eyebrow transplant, within two years the hair will start to grow more like eyebrows’ hair. The transplanted hair will still have to be cut, but it will not be as coarse anymore, and will get more like eyebrows’ hair in time.

Hair will thus more or less retain its character from the area it was taken from. This is because there are stem cells around the hair follicles that are programmed to perform a particular work – in this case, producing new hair of a certain nature that are encoded in our genes, and this no matter where on the body it occurs.