Final answer:
Chondrocytes are cells that produce the cartilage matrix, which calcifies to form bone through a process called endochondral ossification. This process includes the death of chondrocytes as the matrix calcifies, leading to the formation of bone tissue and the marrow cavity.
Step-by-step explanation:
In the context of bone development, chondrocytes are specialized cells that form cartilage, which acts as a precursor to bone in a process called endochondral ossification. Chondrocytes arrange themselves in lacunae within a large amount of the extracellular matrix composed of proteins and polysaccharide derivatives such as chondroitin sulfates. During the growth of long bones, they divide and secrete more matrix, which later calcifies, blocking nutrient diffusion and leading to chondrocyte death and the creation of cavities. These cavities are invaded by blood vessels, turning the cartilage into bone as osteoblasts and osteoclasts remodel the matrix into spongy bone and eventually form a marrow cavity.
The extracellular matrix is important for the structural integrity of cartilage, allowing it to withstand pressure and serve as a template for future bone growth. Chondrocytes in the diaphysis can undergo interstitial growth, dividing and secreting the matrix much like stacks of coins. However, once the matrix begins to calcify, the diffusion of nutrients is inhibited, leading to the death of chondrocytes and the transition of cartilage into bone.