One question central to the study of developmental biology is: How doesphenotypic diversity arise? The neural crest provides an excellent model system forinvestigations into the nature of cell-fate decisions and generation of lineage diversity.In the studies described here, I have examined two aspects of this question in cellculture. The first aspect concerns the cellular dynamics underlying the cell-fatedecisions. A necessary prerequisite to the study lineage diversification is the reliableproduction of differentiated cells from undifferentiated precursors in a controllableenvironment. I have developed a system for the growth of rat neural crest cells. Thesystem allows the serial propagation of a defined sub-population of neural crest cells atclonal density. In the system neural crest cells can differentiate into at least twoidentifiable cell types; peripheral neurons and Schwann cells. By sub-cloning I havebeen able to address specific predictions made by a stem cell model of neural crestdevelopment, and found neural crest cells to possess multipotency, self-renewal and thecapacity to divide asymmetrically.
The second aspect of the question addressed in this study concerns the ability ofthe neural crest cell environment to control the choice of cell fate. I have examinedvarious culture conditions for their ability to affect the choice of cell fate both in clonalcultures and in mass cultures. In the clonal cultures I found that the fate of neural crestcell clones can be altered in an instructive fashion by the composition of the substrate,or by the presence of fetal bovine serum. In mass cultures, we have examined theeffect of medium composition on the expression of adrenergic traits and on theexpression of a transcription factor, MASH-1, thought to participate in neuraldetermination. Finally, in mass cultures of neo-natal adrenal chromaffin cells, we haveexamined the effects of basic fibroblast growth factor on neuronal differentiation,mitosis and acquisition of trophic dependence.
