The embryonic neural crest is the source of many adult structures including most of the cells of the peripheral nervous system. The overall goal of my research is to understand the mechanisms which control the differentiation of neural crest cells into particular neuron types. Our current work is focused on the development of cells which contain catecholamines and somatostatin-like immunoreactivity. Experiments to be conducted during the next year will employ antibodies to particular cell surface antigens as phenotypic markers of subclasses of young neural crest cells. These experiments will take advantage of techniques that allow the positive or negative selection of cell populations possessing a particular antibody binding site. We will determine operationally which antibody markers are associated with the precursor population which gives rise to the catecholamine-and somatostatin-positive cells. This will allow the eventual isolation and analysis of these precursor cells.