Nerve Growth Factor and the Issue of Mitosis in the Nervous System

Evidence indicates that growth factors entirely distinct from nerve growth factor (NGF) regulate neuronal mitosis. The classic growth factor, NGF, is not apparently directly mitogenic for neurons, whereas other factors do regulate neuronal mitosis. In concert, these multiple factors contribute to the normal development and function of the nervous system. This chapter focuses on the twin issues of NGF and neuronal mitogenesis in the nervous system. It discusses the problems of neuronal mitosis and NGF function in the nervous system; however, the regulation of mitosis is placed in the context of neural system complexity. Therefore, it is emphasized that NGF helps foster specific patterns of connectivity and thereby fosters its subsequent actions on survival and phenotypic expression. The chapter stresses the inextricable interrelationships of NGF, connectivity, neuron survival, and differentiation.