EPIPHYSEAL DISC – 5
Five Regions or Zones can be observed in a epiphyseal disc.
They represent a sequence of transformations of cartilage cells that at the end of the disk are replaced by bone cells and tha cartilage is replaced by bewly formed bone.
In spite of being seen as bands in sections, they are actually disks. When observing from the epiphysis toward the diaphysis one realizes that the each Region or Zone shows a (subtle) transition the next, meaning that the boundaries between the zones are not well defined.
They represent a sequence of transformations of cartilage cells that at the end of the disk are replaced by bone cells and tha cartilage is replaced by bewly formed bone.
In spite of being seen as bands in sections, they are actually disks. When observing from the epiphysis toward the diaphysis one realizes that the each Region or Zone shows a (subtle) transition the next, meaning that the boundaries between the zones are not well defined.
Zones of the epiphyseal disc
1 – Zone of resting cartilage
2 – Zone of proliferation
3 – Zone of hypertrophic cartilage
4 – Zone of calcification
5 – Zone of ossification
The first four zones are formed of cartilaginous tissue and new bone tissue is present in the last zone.
The image shows these zones and they will be described in detail on the next pages.
Zones of the Epiphyseal disc seen in a longitudinal section of the bone. Staining: HE. Magnification: small.
