We have used cell type-specific markers to identify and study the major classes of neural cells in dissociated cell cultures of optic nerve, spinal cord, and dorsal root ganglion from 15- to 21-week-old human fetuses. Astrocytes were identified by the intracellular expression of glial fibrillary acidic protein, oligodendrocytes by the cell surface expression of galactocerebroside, dorsal root ganglion neurons by their ability to bind tetanus toxin at their surface, and macrophages (including microglia) by cell surface Fc receptors and their phagocytic properties. Oligodendrocytes continued to express galactocerebroside (and some of them, also myelin basic protein) for up to 1 week in culture in the absence of neurons. While some dorsal root ganglion Schwann cells initially expressed galactocerebroside on their surface, and myelin basic protein and the major peripheral myelin glycoprotein (PO) intracellularly, they no longer expressed detectable amounts of any of these myelin-specific molecules after several days in culture. The Thy-1-like glycoprotein was found on the surface of fibroblasts, dorsal root ganglion neurons, and some astrocytes but not oligodendrocytes or the majority of leptomeningeal cells. Fibronectin was only expressed by fibroblasts and leptomeningeal cells.