Application of the Golgi-EM technique to the study of altered cortical pyramidal neuron morphology in feline gangliosidosis has revealed the presence of aberrant synapses in relation to multiple neurites and secondary neurites of meganeurites. In addition fine neurites arising from the soma and meganeurite are found to project into and envelope elements of the surrounding neuropil. These observations provide further evidence for a disturbance in neuronal surface membrane regulation in ganglioside storage disease.