The objective of this study is a better understanding of the humoral control of growth and elucidation of the roles played by growth hormone and by somatomedins and other growth factors. The serum and tissue growth factors that promote cell replication will be studied in regard to their source, chemistry, dependence on pituitary growth hormone and specificity of target tissue. The serum factor that is active on rat aorta will be purified and further studied. The nature of the growth factor activity in amniotic fluid will be studied. The Spargana Growth Factor (SGF) will be further studied, particularly as a possible model of a "non-diabetogenic" growth hormone and conversely, a "diabetogenic" factor separate from growth hormone will be sought in human pituitary fractions. The binding of SGF to GH receptors will be examined further to determine whether there may be "metabolic" GH receptors to which SGF does not bind as well as "anabolic" receptors to which it does. Large batches of human pituitaries will be extracted annually for hGH and other human pituitary hormones and the treatment of dwarfism and the search for other potential clinical uses continued. Serum somatomedin will be determined in children with nutritional inadequacies and in uremic patients maintained by exchange dialysis.