What are follicular units and why are they so important?
Hair grows out in groups of 1 to 4 hairs, with hairless skin between these units. Follicular unit transplanting consists of using stereomicroscopes to carefully remove these units intact from the skin to transplant to the balding areas. The hairless skin between the follicles is removed so that you get a genuine “hair” transplant. It is important to do this because the last thing a patient with bald skin needs is to have more bald skin transplanted along with the hair.
How is Follicular Unit Transplantation different from mini / micro-grafting?
A micro-graft is a graft containing 1 to 2 hairs and a mini-graft is a graft containing 3 to 6 hairs. Therefore, follicular unit grafts are actually a form of mini/micro grafting. But that is where the similarity ends. Mini / micro-grafting does not respect the follicular units. They are prepared by removing the donor strip with a multi-bladed knife, which results in more hair transection than with a single-bladed knife. After the strip removal, the grafts are prepared and cut-to-size using little or no magnification and with little respect for the natural follicular units. This causes three problems: 1) more transection 2) transplanting the hairless skin; and 3) less density in the recipient area due to the hairless skin being transplanted and the larger size of the grafts. The main advantages of mini/micro grafting are that it is faster for the surgeon and requires less skill and manpower for the assistants and is therefore cheaper. The results, unfortunately, often reflect this.
What is Follicular Unit Transplantation (FUT)?
Follicular Unit Transplantation (FUT) is the transplantation of very small, individual, naturally occurring groups of hair called follicular units. A thin strip of hair bearing skin is removed from the back and sides of a patients scalp and each individual follicular unit is then dissected out using skilled technicians and microscopes. Follicular units are comprised of 1, 2, 3 and sometimes 4 hairs each. These units are placed in thinning / balding areas following natural hair growth patterns.
What is Follicular Unit Extraction (FUE)?
Follicular Unit Extraction (FUE) involves the removal of individual follicular units from the donor area, one by one, without a standard surgical incision. A blunt-tipped punch tool is used to extract the individual hair follicles from the scalp.
Follicular Unit Extraction was developed because some patients were unhappy with the appearance of the “donor” scar on the back of the head. With a proper surgical technique the donor scar should be virtually invisible in the majority of cases.
What is a bifollicular unit?
Some follicular units can occur very close together so rather than separating them into 2 individual grafts, they are carefully dissected out using the stereomicroscope, into a tiny piece of tissue containing just 2 follicular units. Placed in the forelock area they provide extra density beyond that which can be achieved using single follicular units on their own.
The hair follicle usually consists of between 1-4 terminal hairs with associated sebaceous glands, tiny muscles, which can make your hair stand on end and a surrounding collection of blood vessels, nerves and binding collagen fibres. It is felt that this follicular unit constitutes a distinct physiologic entity and should be respected as such. In contrast, when a hair is looked at in vertical section the follicular unit as such is less obvious. However it is useful to look at an individual hair to understand some of the terms that are commonly used when a patient is reading about androgenetic alopecia, male pattern baldness.
Diagram showing a cross-section of the skin and hair follicles.
About the Author
DR Maurice Collins
MB, B.Ch, BAO, DLO, FRCSI, FRCS, FRCSEd.
Registered with the Medical Council of Ireland
Dr Collins is Medical Director and Team Principal of Hair Restoration Blackrock. He was educated at Belvedere College Dublin and did his undergraduate medical studies at University College Dublin. After graduating as a doctor he trained in General Surgery and received his Fellowship (FRCSI) in this specialty from the Royal College of Surgeons in Ireland.
Find out more about DR Maurice Collins and our team of doctors and surgeons.