This painting depicts a growth plate, also known as the epiphyseal plate. This is the area of growing bone in children, particularly in the long bones of the body-legs and arms. Each bone has two growth plates at each end. The top of the painting depicts cartilage cells (blue) that continue to grow and produce new cells. The growth plate is cartilage made up of chondrocytes, which produce the cartilage. Chondrocytes are constantly undergo mitosis, cell division, to lengthen the bone and this is controlled by growth hormone in what is called the Zone of Proliferation (top of the painting). The cells then go through a phase where they continue to enlarge, termed hypertrophy (Zone of Maturation and Hypertrophy) followed by calcification and ossification where the cartilage turns to bone (Zones of Calcification and Ossification). I think these are some of the prettiest cells in the body.