高温致金黄地鼠神经管畸形中细胞凋亡的组织学观察

HISTOLOGICAL STUDY OF APOPTOSIS IN THE GOLDEN HAMSTERS WITH NEURAL TUBE DEFECTS CAUSED BY HYPERTHERMIA

为研究细胞凋亡与高温致神经管畸形的关系，采用核固红－结晶紫染色方法和电镜技术，观察高温后胚胎发育变化。结果显示，高温后８ｈ胚胎发育迟缓，神经管延迟闭合或不闭合，胚胎各段尤其是头部的神经上皮和周围间充质的细胞凋亡比对照组增多，其超微结构改变为染色质浓缩、边聚，核膜皱缩，微绒毛消失并出现异常的胞质突起；１６ｈ后细胞凋亡明显增多，胞质内出现了大量空泡，凋亡小体增多；２４ｈ后细胞凋亡逐渐减少，凋亡小体被邻近的细胞吞噬，于７２ｈ后细胞凋亡恢复至对照组水平。结果表明，高温能促进神经上皮和周围间充质的细胞凋亡，使存活细胞数减少，结果导致了神经管延迟闭合或不闭合。

Hyperthermia is one of common teratogens causing varieties of congenital malformatoins including neural tube defects(NTD) such as anencephly and spina bifida.In this experiment,the nuclear fast red crystal violet staining method and electron microscopy were employed to explore the relationship between apoptosis and NTD induced by hyperthermia. Pregnant golden hamsters were put into water at 42℃ for 20minutes on 8th day of gestation.The embryos were respectively removed at 2,4,8,16,24,48,72,96 hours after treatment.Some embryos were fixed in modified Bouin solution,embeded in paraffin,sectioned in series,and stained with nuclear fast red and crystal violet for detection of apoptosis in the embryonic neural epithelium and the mesenchyme around neural tube.Some embryos were prepared for observation with scanning electron microscope and transmission electron microscope.The results were as follows:The embryos of the experimental groups developed much later than those of the normal,and the amounts of the apoptotic cells in the neural epithelium and in the mesenchyme were much more than that of the mormal.It showed by electron microscope that the apoptotic cell had a shrunk nucleus with aggregated and marginated chromatin, there were abnormal cytoplasmic blebs instead of microvilli in the free surface of the cell.The cytoplasmic protuberances were separated from cell surface to form apoptotic bodies.At the 24th hour after treatment with hyperthermia the apoptotic bodies were phagocytosed by the neighbour cells.The embryos of the experimental animals were not siginifcantly differnt from the normal in apoptosis at the 72th hour after treatment with hyperthermia.It indicated that hyperthermnia may induce excess apoptosis in the neural tube and mesenchyme,thereby resulting in failure of formation of neural tube,It was an important way by which hyperthermia caused neural tube defects.