<P> The epiphyseal plate (or epiphysial plate, physis, or growth plate) is a hyaline cartilage plate in the metaphysis at each end of a long bone . It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, with maintenance remodeling throughout its existing bone tissue, but the growth plate is the place where the long bone grows longer (adds length). </P> <P> The plate is not only found in children and adolescents; in adults, who have stopped growing, the plate is replaced by an epiphyseal line . This replacement is known as epiphyseal closure or growth plate fusion . Complete fusion happens between ages 12--16 for girls and 14 - 19 for boys . </P> <P> Endochondral ossification is responsible for the initial bone development from cartilage in utero and infants and the longitudinal growth of long bones in the epiphyseal plate . The plate's chondrocytes are under constant division by mitosis . These daughter cells stack facing the epiphysis while the older cells are pushed towards the diaphysis . As the older chondrocytes degenerate, osteoblasts ossify the remains to form new bone . In puberty increasing levels of estrogen, in both females and males, leads to increased apoptosis of chondrocytes in the epiphyseal plate . Depletion of chondrocytes due to apoptosis leads to less ossification and growth slows down and later stops when the entire cartilage have become replaced by bone, leaving only a thin epiphyseal scar which later disappears . </P> <P> The growth plate has a very specific morphology in having a zonal arrangement as follows: </P>

Where is longitudinal growth occurring in long bones