The physis (pl. physes) or growth plates are found in bones that undergo endochondral ossification.
The physis is located between the metaphysis and epiphysis in skeletally-immature patients and contains zones of mesenchymal cells in various maturation stages (see physeal anatomy illustration). The histology of these cells is beyond the scope of this article.
As the metaphysis and epiphysis mature and fuse, the physis thins, disappears, and enchondral ossification ceases. A subchondral bone plate forms with horizontally oriented trabeculae which appears as a radiopaque transverse fusion line (physeal scar). This line should not be mistaken for a stress fracture.