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在胚胎发育过程中,神经管的封闭是在妊娠后第一个月完成的。封闭从胚胎的头端开始,向尾端延伸,在受精后第28天,封闭完成。头端封闭失败会产生无脑儿。神经管的中段或尾端封闭失败伴有或不伴有脑积水的则产生脊膜膨出。(附图从略) 在英国,神经管缺损是产生严重先天性异常的最常见原因。据文献记载,神经管缺损发生率最高的是爱尔兰最低的是日本。(表2、1)
During embryonic development, the tube of the neural tube is closed during the first month of gestation. Closure begins at the head end of the embryo and extends to the caudal end. On the 28th day after fertilization, the closure is completed. Closed head failure will have no brain children. Failure to close the middle or caudal end of the neural tube produces prolapse of the spine with or without hydrocephalus. (Omitted from the drawing) In the UK, neural tube defects are the most common cause of severe, congenital abnormalities. According to the literature, the highest incidence of neural tube defects in Ireland is the lowest in Japan. (Table 2,1)