We propose to develop and use antibodies as markers for the different cell types of the nervous system. We have a special interest in surface antigens, and will probe for the involvement o such antigens in specialized cell function, or in cell-cell interactions. Thy-1 glycoprotein is a surface antigen on neurons, and we propose to follow its development on neurons of the peripheral and central nervous system in vitro and in vivo, and test for the effect of anti-Thy-1 on neuronal functions. Chromaffin cells from fetal adrenals are also to be tested, and their surface antigens compared with pheochromocytoma PC 12 cells. Toxin binding and action on these cells is to be investigated, and the cells' complex lipids analyzed. Finally, the structure of Schwann cells in culture, and the distribution of the Schwann cell surface antigen Ran-1 will be analyzed as Schwann cells and neurons are cultured together in vitro. Cells in culture which express galactocerebroside, and are thought to be oligodendroglia, will also be characterized at the ultrastructural level.