This slide is not the same as slide 25 in your box. The zones of resting cartilage (RC) looks larger, the zone of proliferating cartilage (PC) does not look as active and the zone of hypertrophic cartilage (HC) includes what I would call the zone of calcified cartilage. The inset shows osteoblasts (Ob), calcified cartilage (C), an osteoclast (Oc) and bone (EB).