In endochondral ossification, what major process occurs in the diaphysis but not in the epiphysis?

In endochondral ossification, the formation of the medullary cavity occurs in the diaphysis but not in the epiphysis. The medullary cavity is a central cavity within long bones that houses bone marrow. It is formed during the process of ossification as the bone grows and matures.

In the diaphysis, chondrocytes (cartilage cells) die, and this area is replaced by bone tissue. This process also involves the formation of a cavity as osteoclasts break down the newly formed spongy bone, allowing the medullary cavity to develop. In contrast, the epiphysis remains relatively untouched by this direct formation of a medullary cavity. Instead, the epiphysis develops into the ends of the bone that are capped by articular cartilage, facilitating joint movement without the formation of a medullary cavity.

This differentiation in processes between the diaphysis and the epiphysis is crucial for the overall development of long bones, ensuring they are structurally sound and functional for movement and support.