The epiphyseal plate, also known as the growth plate, is a thin layer of hyaline cartilage found in the epiphysis, or end, of a long bone. It is responsible for the growth and development of long bones in children and adolescents. In adults, the epiphyseal plate is replaced by solid bone, and growth of long bones ceases.
Structure
The epiphyseal plate is made up of three zones: the resting zone, the proliferative zone, and the degenerative zone.
- Resting zone: The resting zone is located at the outer edges of the epiphyseal plate, and it is made up of a single layer of flattened chondrocytes (cartilage cells). These cells are not actively dividing and are responsible for maintaining the integrity of the cartilage.
- Proliferative zone: The proliferative zone is located in the middle of the epiphyseal plate, and it is made up of several layers of chondrocytes that are actively dividing. These cells are responsible for the growth and development of the long bone.
- Degenerative zone: The degenerative zone is located at the inner edge of the epiphyseal plate, and it is made up of chondrocytes that are in the process of dying off. As these cells die, they are replaced by bone tissue, which eventually replaces the entire epiphyseal plate.
Location
The epiphyseal plate is located at the ends of long bones, such as the femur, tibia, and humerus. It is found in children and adolescents, as it is responsible for the growth and development of these bones. In adults, the epiphyseal plate is replaced by solid bone, and growth of long bones ceases.
Function
The main function of the epiphyseal plate is to allow for growth and development of long bones in children and adolescents. It does this through the process of endochondral ossification, in which chondrocytes in the proliferative zone actively divide and produce new cartilage tissue. This tissue is then replaced by bone tissue as the chondrocytes in the degenerative zone die off and are replaced by bone-forming cells called osteoblasts.
As the long bone grows, the epiphyseal plate also undergoes remodeling, in which the cartilage is resorbed and replaced by bone tissue. This process allows the bone to become stronger and more able to withstand the stresses placed on it.
Clinical Significance
Disorders of the epiphyseal plate can have significant clinical consequences. One such disorder is epiphyseal dysplasia, which is characterized by abnormal growth and development of the epiphyseal plate. This can lead to short stature, deformities, and impaired function of the affected bone.
Another disorder that can affect the epiphyseal plate is scoliosis, a condition in which the spine is curved to the side. This can cause abnormal growth and development of the spine, leading to deformities and impaired function.
Injuries to the epiphyseal plate can also have significant consequences. Fractures of the epiphyseal plate can disrupt the normal growth and development of the long bone, leading to deformities and impaired function.
