Five Zones of Epiphyseal Plate

Zone of reserve cartilage

Chondrocytes rest, Area of cartilage on epiphyseal side of epiphyseal plate that is relatively inactive

Zone of Proliferation (growth)

Chondrocytes divide, cell divison, Area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing
New cells formed move upward, pushing epiphysis away from diaphysis, causing lengthening

Zone of hypertrophy and maturation

Area with older chondrocytes closer to diaphysis
Cartilage lacunae enlarge and erode, forming interconnecting spaces. Cartilage cells stop growing

Zone of Calcification

Surrounding cartilage matrix calcifies, chondrocytes die and deteriorate, containing osteoblasts

Zone of ossification

Chondrocyte deterioration leaves calcified cartilage at epiphysis-diaphysis junction
osteoclasts clean up and osteoblasts ssecrete osteoid
spongy bone forms
medullary cavity enlarges
new bone forms