Figure 12.

Schematic diagrams depicting the disintegration of Hertwig's epithelial root sheath during root development. (A) Hertwig's epithelial root sheath (HERS) bends inside toward dental pulp (DP) at the tip of developing root (R). (B) Three-dimensionally, the epithelial sheath forms a tapered cylinder. (C) Root formation proceeds almost straight, whereas the epithelial sheath maintains the tapered shape. As a result, due to the discrepancy in surface area, the epithelial sheath is stretched out and fragmented into epithelial cell rests of Malassez.

Modified from Yamamoto et al. [58].