Editing Endochondral ossification (section)

==Histology==
[[File:Epiphyseal growth plate.jpg|thumb|Zones of endochondral ossification.]]
During endochondral ossification, five distinct zones can be seen at the light-microscope level:<ref name="brief" />
{| class="wikitable"
|-
!Name
!Definition
|-
|Zone of resting cartilage
| This zone contains normal, resting [[hyaline cartilage]].
|-
| Zone of proliferation / cell columns
| In this zone, [[chondrocyte]]s undergo rapid [[mitosis]], forming distinctive looking columns.
|-
| Zone of maturation / hypertrophy
| In this zone, the chondrocytes undergo [[hypertrophy]] (become enlarged). Chondrocytes contain large amounts of [[glycogen]] and begin to secrete [[vascular endothelial growth factor]] to initiate vascular invasion.
|-
|Zone of calcification
| In this zone, [[chondrocyte]]s are either dying or dead, leaving cavities that will later become invaded by bone-forming cells.  Chondrocytes here die when they can no longer receive nutrients or eliminate wastes via diffusion.  This is because the calcified matrix is much less hydrated than hyaline cartilage.
|-
|Zone of ossification
| Osteoprogenitor cells invade the area and differentiate into osteoblasts, which elaborate matrix that becomes calcified on the surface of calcified cartilage.
|}
[[File:Epi plate.jpg|upright=2]]