A natural grouping of one to four hairs that emerges from the scalp as a unit.
A follicular unit is the natural anatomical grouping used in modern hair transplantation. Most units contain one to four hairs, along with associated structures such as sebaceous glands and connective tissue. Modern transplantation aims to preserve and move these units rather than using old plug-like grafts. One-hair units are valuable for creating a soft natural hairline, while larger units help build density behind it. Understanding follicular units helps patients interpret graft numbers: 2,000 grafts does not mean 2,000 hairs, because each graft may contain multiple hairs.
Anastassakis K. Androgenetic Alopecia From A to Z, Vol. 3, Springer, 2023 — https://doi.org/10.1007/978-3-031-10613-2
