Why epiphyseal plates remain thin while they grow?

Chondrocytes divide rapidly and form columns of stacked cells at the epiphyseal cartilage of short and long bones. During the growth towards the ends of bones, the chondrocytes that were originally dividing in closest proximity to the center of the bone (still within the epiphyseal cartilage), die and become resorbed matrix. This matrix soon becomes calcified. Because the proliferation and destruction of chondrocytes occur at the same rate, the epiphyseal plate does not change thickness. It does, however, grow away from the middle of the bone.