Hair transplantation is a common procedure for individuals experiencing hair thinning or loss. The fundamental structure relocated during the process is the hair graft, which is more accurately termed a follicular unit. This unit serves as the building block for the final result, and its size and physical integrity are directly linked to the success and natural appearance of the transplant. Understanding the dimensions of this small tissue unit and the meticulous steps taken to prepare it helps explain the precision required in modern hair restoration surgery.
Defining the Follicular Unit
A hair graft is not simply an individual hair shaft, but rather a naturally occurring biological structure called the follicular unit. These units are small groups of hair follicles that grow together in the scalp, making their transplantation the basis for achieving a natural look. Scalp hair naturally grows in these clusters, which typically contain one, two, three, or sometimes four hairs.
The follicular unit includes supporting elements necessary for its survival and function after relocation. This includes the sebaceous (oil) gland, the arrector pili muscle, and surrounding neural and vascular structures. Keeping this entire package intact during the extraction and placement process is a primary goal of hair restoration. Preserving the natural composition of the unit maximizes successful hair growth and provides fullness.
Physical Dimensions of the Extracted Graft
The initial physical size of the extracted graft depends significantly on the harvesting method used by the surgeon. In Follicular Unit Extraction (FUE), the graft is removed individually using a small, circular punch tool. The diameter of this punch is generally between 0.7 millimeters and 1.15 millimeters, with 0.9 millimeters being a commonly used size.
This small, cylindrical FUE graft contains the follicular unit and surrounding tissue. The precision of the punch size is important because a larger diameter may lead to noticeable scarring in the donor area, while a punch that is too small risks damaging the follicular unit during extraction. The size must be calibrated to minimize trauma while ensuring the entire follicular unit is removed intact.
In contrast, the Follicular Unit Transplantation (FUT) method begins by surgically removing a thin strip of tissue from the donor area, which may average about 1 centimeter in width and a variable length. This strip is then handed over to a specialized team for preparation. The individual follicular units are dissected from this larger piece of tissue, meaning the initial extraction size is not the final graft size used for implantation.
Refinement Through Microscopic Dissection
Once the tissue is extracted, particularly in the case of the FUT strip, the next step involves refinement through microscopic dissection. Surgical technicians use stereoscopic microscopes, often with 10x magnification, to carefully separate the individual follicular units from the surrounding tissue. This process trims away excess fat and dermis that are not required for the unit’s survival.
The goal of microscopic trimming is to create the smallest viable unit possible, often referred to as a micrograft. Minimizing tissue volume allows the graft to fit snugly into the recipient site created by the surgeon. This preparation prevents damage to the hair follicles and reduces the risk of the follicle being cut or transected during the process. Magnification helps ensure the integrity of the follicular unit is maintained, leading to improved graft survival and growth.
Graft Size and Aesthetic Outcomes
The final, refined size of the hair graft is directly related to the quality and naturalness of the aesthetic outcome. Smaller, more refined grafts allow the surgeon to implant more units into a given area of the scalp, which is known as increasing the density. Attempting to achieve high density with larger, unrefined grafts can compromise the skin’s blood supply, which may negatively affect graft survival.
Strategic placement of different-sized units, which are sorted during the microscopic dissection process, contributes to an undetectable final result. For instance, single-hair follicular units are reserved for the outermost row of the hairline to create a soft, feathery transition. Units containing two or three hairs are placed behind the hairline to build volume and density in the mid-scalp area. Using larger grafts that contain excess tissue would result in a visually unnatural or “pluggy” appearance, which modern techniques are designed to avoid.