Light microscopy of a growth plate in a growing bone. The growth plate is formed of cartilage consisting of proliferating cartilage cells (chondrocytes) and the matrix which they produce (dark and light blue zones). Mature chondrocytes in the light blue zone will die but their cartilage matrix acts as a surface upon which bone-forming cells (osteoblasts) deposit bone matrix in the lower half of the image (pink/blue). Over time the bone slowly grows in length until the growth plate stops making cartilage. Magnification x90 when narrow width printed at 10 cm.