Endochondral ossification

On the other hand, endochondral ossification starts with mesenchymal tissue turning into an intermediate cartilage stage, which is eventually substituted by bone.

[7] In addition, endochondral ossification is not exclusively confined to embryonic development; it also plays a crucial role in the healing of fractures.

[3] The initiation of endochondral ossification starts by proliferation and condensation of mesenchymal cells in the area where the bone will eventually be formed.

Indirect fracture healing, the most common type of bone repair,[10] relies heavily on endochondral ossification.

In contrast, intramembranous ossification takes place directly beneath the periosteum, adjacent to the broken bone’s ends.

A schematic for long bone endochondral ossification.
Light micrograph of undecalcified epiphyseal plate showing endochondral ossification: healthy chondrocytes (top) become degenerating ones (bottom), characteristically displaying a calcified extracellular matrix .
Zones of endochondral ossification.
A schematic of endochondral fracture, where B shows the location of both endochondral and intramembranous ossification.