Abstract: ObjectiveTo detect the ultrastructure of neural stem cells (NSCs) cultured in vitro .MethodsNSCs separated from the cortex of 17—19 days Wistar rat fetus were cultured and induced to differentiate in vitro. Electron microscopes were used to visualize the ultrastructure of these cells before and after differentiation.ResultsNSCs had the similar cellular size, morphology and intracellular structures pre-differentiation. Cells were able to proliferate via mitosis. The nucleus/cytoplasm ratio was very high. The nucleus was poly-morphological. Cells had very little cytoplasm and no mature organelles. After differentiation, several processes protruded out from cellular surface. Cells became flat shape, the volume of cytoplasm increased dramatically and various kinds of mature organelles appeared in the cytoplasm. Cells differentiated into two kinds of cells,neural cells and glial cells,with quite different morphology and intracellular structure. ConclusionNSC is one kind of original cells which can be induced to differentiate into mature neural cells and glial cells.

Key words: neural stem cells, ultrastructure, differentiation, organelle, rats