Objective   To define effect of neuron apoptosis on rats.neural tube defects caused by cyclophosphamide.

  Methods   Using neural tube defects model induced by cyclophosphamide, effect of neuron apoptosis were observed through optical microscopy, transmission electron microscopy in vivo and under phase-contrast microscopy, flow cytometry and single-cell gel electrophoresis technology in vitro.

  Results   (1) Optical microscopy results indicated that a lot of nucleus were wrecked and condensed; (2)Under transmission electron microscopy, apoptotic cells exhibited typical morphological changes, including irregular shape of nucleus, chromatin condensation, etc; (3)In the group treated with cyclophosphamide, floating cells increased in number, the neurites were shorten or lost, and the survival cells decreased in number, and the networks of cell processes were sparse; (4)In the model group, "apoptotic peak" and "comet cells" were found when neuron cells were observed through flow cytometry and single-cell gel electrophoresis technology.

  Conclusion   Neurons apoptosis might be involved in cyclophosphamid teratogenesis.