What are growth plates primarily comprised of?

Growth plates, also known as epiphyseal plates, are primarily composed of cartilage that has not yet ossified. This cartilage is essential for the process of longitudinal bone growth during childhood and adolescence. The cartilage in growth plates serves as a temporary structure that allows for the elongation of bones as new cells continuously produce additional cartilage. Eventually, this cartilage is replaced with bone through a process called endochondral ossification, leading to the closure of the growth plates and the cessation of height increase.

The focus on cartilage, rather than fully ossified bone or any other tissue types, is crucial because the growth plate must remain flexible and able to expand for bones to grow properly. Once growth is complete and the growth plates have fully ossified, they transform into solid bone, effectively ending the growth process. Understanding the composition and function of growth plates is essential for recognizing how skeletal development occurs during pivotal growth phases.