The structure that replaces the epiphyseal plate in adult bone is the _
A epiphyseal line
B yellow bone marrow
C periosteum
D medullary cavity
The correct answer and explanation is:
The correct answer is A: epiphyseal line.
The epiphyseal plate, also known as the growth plate, is a hyaline cartilage plate found at the ends of long bones in children and adolescents. It is the region where bone growth occurs, allowing the bones to lengthen as the body grows. This growth process is controlled by hormones such as growth hormone and sex hormones during puberty.
As a person matures, the cartilage in the epiphyseal plate gradually ossifies (turns into bone). Once this process is complete, the epiphyseal plate is replaced by a thin line of bone known as the epiphyseal line. This marks the cessation of bone lengthening and the end of growth in that particular bone. The epiphyseal line remains visible on X-rays as a faint line across the bone.
The other options are not correct:
- Yellow bone marrow (B): This is the fatty tissue found in the medullary cavity of long bones in adults, where it functions primarily as an energy reserve and does not play a role in replacing the epiphyseal plate.
- Periosteum (C): This is a dense layer of vascular connective tissue enveloping the bones, except at the joints. It is involved in bone growth, repair, and nutrition, but it does not replace the epiphyseal plate.
- Medullary cavity (D): This is the central cavity within long bones that contains bone marrow. The medullary cavity expands during growth but does not replace the epiphyseal plate.
In summary, the epiphyseal line marks the end of growth at the epiphyseal plate and is the correct structure that replaces the growth plate in adult bones.