GangliosideGM1 represents a widespread component of the neural cell plasma membranes. Cholera toxin-B subunit binds selectively to GM1. Human spinal cords at post-conception (PC) weeks 6 to 11 were examined and early GM1 expression shown on the cell plasma membrane in the developing grey matter at PC week 6. GM1 was demonstrated also in the marginal layer (white matter); on neural crest derivative plasma membrane, i.e. dorsal root (DRG) and sympathetic ganglia; along emerging fibres from DRG and neurite terminals innervating skeletal muscle. GangliosideGM1 is highly expressed in spinal cord primary cultures and is a stringent neural cell marker. GangliosideGM1 represents an early marker of neural differentiation in both spinal cord and neural crest derivatives.