Ultrastructural characterization of central neurocytomas using collagen gel culture.

Central neurocytoma is a rare brain tumor with neuronal differentiation. Cultured central neurocytoma cells are poorly described because of the tumor's scarcity. Two central neurocytomas were cultured using a monolayer culture for first few passages, and then a portion of each specimen was cultured in a collagen gel. Immunostaining for synaptophysin or glial fibrillary acidic protein performed on the primary culture revealed the presence of cells expressing synaptophysin and cells expressing glial fibrillary acidic protein. Cells expressing synaptophysin tended to disappear in passage 2, whereas the cells expressing glial fibrillary acidic protein remained. Ultrastructurally, samples in passage 5 obtained from the collagen gel cultures revealed neuron-like cells with prominent nucleoli, cell processes containing dense core vesicles and clear vesicles, and synapse-like structures. By contrast, samples obtained from passage 5 of monolayer cultures failed to reveal ultrastructural neuronal characteristics. These results suggest that spatial cell growth and the presence of collagen, i.e., extracellular matrix, may be necessary to retain neuronal differentiation in a central neurocytoma.