Summary of Doctoral Thesis

Insulin‐like growth factors (IGF‐I and IGF‐II), or somatomedins, are small polypeptides structurally related to insulin. IGFs exert insulin‐like, differ‐entiative and mitogenic actions on their target tissues (1). Several, if not all, human fetal and adult tissues produce IGFs, as evidenced by studies on the IGF content of tissue extracts and expression of IGF messenger ribonucleic acid (mRNA) (2,3). Many tissues and cell lines possess IGF receptors, through which IGFs exert their biological actions (4). Serum and tissue contents of IGF‐I, and to a lesser extent IGF‐II, are regulated by GH, nutritional status, age and other factors (5). Thus IGFs are thought to act both in endocrine and locally in an autocrine or paracrine manner.