What is the Donor Zone?
In reference to hair restoration, the donor, also known as the “safe donor” or “donor zone”, is the area at the back and sides of a person’s scalp that has hair considered safe for surgical transplantation. This hair is traditionally considered to be resistant to Dihydrotestosterone (DHT), but this is not one-hundred percent guaranteed to be the case for all people, as instanced by those affected by diffuse unpattern alopecia (DUPA) where even the this safe zone experiences thinness or balding by DHT.
The Donor Zone and Dihydrotestosterone (DHT)
Hair on the occipital scalp is thought to be resistant to DHT, the androgen (male sex hormone) responsible for causing genetic forms of male-pattern hair loss (MPH). In most cases of MPH, the hair follicle gradually becomes sensitive to DHT over time as it concentrates in the scalp’s tissue. Eventually, this concentration prevents the hair follicle from receiving an adequate blood supply, and the hair either partially thins or cannot grow as a result.
Hair on the back of the scalp, however, seems to be highly resistant to DHT’s harmful effects. Males often retain their donor area after experiencing the effects of MPH. Therefore, transplanting this DHT-resistant hair onto other areas of the scalp oftentimes allows the follicles to produce healthy new hair that is not noticeably different to the naked eye.
Different Ways to Harvest Hair
There are two ways main ways to perform a hair transplant – a Follicular Unit Strip Surgery (FUSS), or a Follicular Unit Extraction (FUE). For clarity, FUSS is sometimes incorrectly referenced as “FUT”.
FUSS is the older method, though it is still viable and even preferred by some hair transplant doctors. During a FUSS, the donor zone is surgically removed from the rest of the scalp in a large strip. The strip is then dissected to remove the hair follicles from the surrounding tissue using stereoscopic dissecting microscopes. The follicles are separated and grafted back onto the scalp.
An FUE procedure individually extracts each follicular unit from the donor zone using a small surgical punch. These follicular units are then grafted back onto the scalp, much like with FUSS. The main difference between a FUSS and a FUE procedure is that the FUE hair transplant doctor does not cut the donor zone away from the scalp in a long strip in order to obtain FUE grafts, thus it does not leave a linear scar as a result.
The FUSS method leaves a large linear scar across the site of the safe zone. This scar does not go away on its own, and may become even greater if further FUTs are needed. The donor scar shown in the photo to the side is considered to be an acceptable donor scar as it does not interfere with the overall aesthetic of the scalp when hair is grown to a length that covers it. However, with current hairstyles becoming shorter and shorter this type of procedure is preferred less and less by younger patients as they lose the option to have such short haircuts.
FUE also leaves scarring, but the instrument leaves small circular scars that lack pigment and can be concealed more easily under the hair. For this reason, an FUE is often recommended, especially if the patient wants to wear a short haircut or has already undergone FUSS enough times that the donor laxity will not allow for additional FUSS procedures.
Staples vs Sutures
When it comes to closing the donor, most doctors choose sutures (stiches) or staples. Sutures are typically not as painful, and do not need a follow-up visit to remove. However, staples do not provoke an inflammatory response from the immune system that can potentially lead to infection and even minor destruction of hair in the immediate vicinity of the incision. Some hair transplant doctors will use both closure techniques with sutures used to close the deeper subdermal wound while staples are used superficially.