Hair transplantation is a cosmetic procedure that involves moving hair from a densely growing area of the scalp to an area experiencing thinning or balding. The success of this surgery relies on the quality and careful placement of the transplanted tissue, known as a graft. Understanding the composition of the graft is central to grasping how the procedure works and why modern techniques yield natural-looking results.
Defining the Hair Transplant Graft
A hair graft is a small segment of skin tissue containing one or more hair follicles, extracted from the donor site and prepared for relocation. It is not simply a single strand of hair, but a complete piece of skin that serves as a living biological unit. This tissue segment includes the hair follicle, the structure responsible for hair growth, along with surrounding elements necessary for its survival.
The graft must contain layers of skin tissue, specifically the epidermis, dermis, and often a small amount of subcutaneous adipose tissue (fat). These surrounding components contain the blood vessels, nerves, and connective tissue required to nourish the follicle. When a graft is transplanted, it is temporarily without its original blood supply and relies on the recipient area to revascularize. The presence of the surrounding tissue helps maintain the follicle’s viability during this transition, ensuring it can survive and grow in its new location.
Classification Based on Hair Count
Historically, hair transplantation used “punch grafts,” which were much larger circular pieces of tissue containing anywhere from 10 to 20 hairs. These older grafts often resulted in an unnatural, tufted appearance, commonly referred to as the “pluggy” look. Modern techniques have evolved to use much smaller grafts, which are categorized primarily by the number of hairs they contain. This classification allows surgeons to strategically place grafts for both density and naturalness.
Current practice focuses on three main sizes that are significantly smaller than historical counterparts. Micrografts contain one or two hairs and are used primarily to create a soft, natural-looking hairline. Minigrafts are slightly larger, holding three to four hairs, and are often placed behind the hairline to increase density and coverage. The most refined classification, however, is the Follicular Unit Graft (FUG), which is based on the natural groupings of hair found on the scalp.
Why the Follicular Unit Structure is Important
The Follicular Unit is the naturally occurring grouping of one to four hairs on the human scalp, and modern hair restoration techniques prioritize keeping this unit intact. This structure is more complex than just a cluster of hairs; it is a biological micro-organ that includes:
- The arrector pili muscle
- Sebaceous (oil) glands
- Nerves
- A vascular network
A fine band of collagen, called the perifolliculum, surrounds and holds the entire unit together.
Maintaining the integrity of the follicular unit during harvesting and implantation maximizes the survival rate of the transplanted hair. Damaging the bulb region or fracturing the unit can severely reduce its ability to grow in the new location. When this complete biological unit is transplanted, the result is an aesthetic outcome that perfectly mimics natural hair growth patterns and is virtually indistinguishable from the surrounding native hair.