GLIAL GROWTH-FACTOR RESTRICTS MAMMALIAN NEURAL CREST STEM-CELLS TO A GLIAL FATE

Growth factors and cytokines are thought to influence the development of uncommitted progenitor cell populations, but the issue of how these factors act on individual cells remains controversial. Such factors m ay act simply as selective mitogens or survival factors for cells that undergo lineage restrictions stochastically. Alternatively, they may instruct or bias multipotent cells to choose one lineage at the expens e of others. Here we show that glial growth factor (GGF), previously d efined as a Schwann cell mitogen, strongly suppresses neuronal differe ntiation of rat neural crest stem cells while promoting or allowing gl ial differentiation. Quantitative clonal analysis suggests that the ac tion of GGF is likely to be instructive rather than selective. Taken t ogether with the expression pattern of GGF, these data suggest a later al signaling model for the diversification of cell types within develo ping peripheral ganglia.