Which event has to precede all others during endochondral ossification?

Formation of a cartilage is the event that proceeds all the others during endochondral ossification.

Explanation:

Among the two essential processes during the mammalian skeleton system development, is Endochondral ossification through which the bone system is created. The cartilage model formed then grows in length and width through the multiplication of the chondrocytes. The above process in the stage is known as interstitial growth.