Final answer:
Hyaline cartilage within the epiphyseal plates is replaced by bone during the process of endochondral ossification, resulting in the longitudinal growth of long bones.
Step-by-step explanation:
The connective tissue that is replaced by bone in the epiphyseal plates is hyaline cartilage. The epiphyseal plate is a layer of this cartilage located at the end of long bones, which permits growth in length. During the process known as endochondral ossification, this hyaline cartilage is successively replaced by bone as the chondrocytes (cartilage cells) proliferate. When growth in length is complete, usually during early adulthood, the epiphyseal plate is fully ossified and what remains is the epiphyseal line.
Lengthening of long bones is achieved as chondrocytes on the epiphyseal side of the epiphyseal plate divide. These new cells replace the old chondrocytes that die and are calcified on the diaphyseal side of the plate. This continuous replacement process allows for the longitudinal growth of bones until the proliferation of chondrocytes ceases and bone replaces the cartilage, marking the end of growth in length.