Growth factors and their cellular actions

Department of Paediatrics, University of Sheffield, Clinical Sciences Centre, Northern General Hospital, SheffieldS5 7AU, U.K. Keywords: growth factors; growth; embryogenesis; differentiation; ovary Introduction Normal tissue growth involves a complex interaction of cell proliferation, hypertrophy, migration, differentiation and senescence which proceeds within strict temporal and anatomical constraints. While classical endocrine hormones such as growth hormone and thyroxine can influence the overall rate of growth and maturation they do not contribute to the fundamental intercellular signalling within tissues that underlies these processes. This appears to be the primary role of peptide growth factors. During the rapid development of the embryo and fetus peptide growth factors are associated with tissue induction, the clonal growth of stem-cell populations, and the appearance of differentiated function in the presumptive organs. In post-natal life the actions of growth factors are less obvious although notable exceptions demonstrate that the same biological pathways exist; the best studied examples