The deficiency of growth hormone during bone formation would cause a decreased proliferation of the epiphyseal plate cartilage. Growth hormone is a peptide hormone secreted by the pituitary gland under the control of the hypothalamus. It directly through IGF-I stimulates osteoblasts proliferation and activity, promoting bone formation. In addition it also stimulates osteoclast differentiation and activity, promoting bone resorption. Therefore, growth hormone is an important hormone in bone formation.