Growth in Length of Long Bones

Proliferation (Growth) Zone

cartilage on diaphysis side is rapidly dividing (new cells formed move up, pushing epiphysis away from diaphysis and causes lengthening) growing fast

Resting (Quiescent) Zone

cartilage on epiphyseal plate, inactive (top zone)

Ossification Zone

chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction (bone structure is complete) bottom zone

Spicules

eroded by osteoclasts and covered with new bone by osteoblasts forming spongy bone

Epiphyseal Plate

maintains constant thickness, closure of this allows growth of length to occur

Hypertrophic Zone

older chondrocytes closer to diaphysis (cartilage lacunae enlarges, increasing length, and erodes causing interconnecting spaces)

Calcification Zone

surrounding cartilage matrix calcifies (chondrocytes die and deteriorate) matrix hardens