Fetal Companion Cells (CpL)

Fetal companion cells are derived from matrix and are located between the inner root sheath cells and outer root sheath cells and are characterized by expression of Krt6 and Krt16. During the post-natal hair cycle, companion cells are only produced during the anagen phase, migrate upwards in parallel to growing inner root sheath cells and envelope the newly forming hair shaft. At the end of anagen phase, companion cells stop proliferating.