Experimental investigation on the cleft lip and palate Research for preventive factor of this disease using spontaneous cleft lip and palate mice strain

根据我们的研究设计，我们进行了以下实验：(1)采集自发性唇腭裂A/J小鼠标本中的卵子，将受精卵移植到基因上无唇腭裂的C57BL/6小鼠标本中，研究唇腭裂及其他外部畸形的发育情况。获得的胚胎没有出现唇裂和腭裂，也没有其他外部畸形。作为对照，制备C57BL/6小鼠受精卵，移植到a /J小鼠体内，证实腭裂发育。培育这些胚胎是为了检查是否会遗传给第二代。结果证实二代存在唇腭裂。(2)采用全胚培养法培养自发性唇腭裂A/J小鼠胚胎，研究唇腭裂的发育机制。研究了雌二醇的抑制作用。而全胚培养法缩短了培养周期，且在有限的观察期内无法发现腭同化现象。因此，我们采用体外器官培养法研究腭同化，并证实雌二醇的预防作用。(3)我们注意到雌二醇治疗对A/J小鼠唇腭裂的预防效果，我们假设雌二醇促进了神经嵴细胞的运动。研究了雌二醇对神经嵴细胞源性胸腺畸形和心血管系统的预防作用。妊娠第8天和第9天给予雌二醇组小鼠的唇腭裂和畸形发生率明显降低，但心血管系统畸形发生率无明显差异。妊娠第7天给予雌二醇的小鼠心血管系统畸形发生率较低。

We performed the following experiment according to our study design :(1) We collected ova from spontaneous cleft lip and palate A/J mice speciments, transplanted the fertilized ova to C57BL/6 mice specimens said to be genetically free from cleft lip and palate, and studied the development of cleft lip and palate and other external malformations. The embryos obtained showed neither cleft lip and palate nor other external malformations. As a control, fertilized ova of C57BL/6 mice were prepared and transplanted to A/J mice and confirmed the development of cleft and palate. The embryos were bred to check for transmission to the second generation. Results confirmed existence of cleft lip and palate in the second generation.(2) The total embryo culture method was used to culture embryos of A/J mice with spontaneous cleft lip and palate, and study the development mechanism of cleft lip and palate. The inhibitory effect of estradiol was also examined. The total embryo culture method, however, shortened the culture period, and palate assimilation could not be recognized within the limited observation period. We therefore adopted the organ culture method to study palate assimilation in vitro, and confirmed the preventive effect of estradiol.(3) Having noted that estradiol therapy was effective in preventing cleft lip and palate in A/J mice, we hypothesized that estradiol promted neural crest cell movement. An experiment was carried out to examine the preventive effects of estradiol on cardiovascular system and thymus malformations originating in neural crest cells. Although in the groups of mice which were administered estradiol on the 8th and 9th day of pregnancy incidences of cleft lip and palate and malformation significantly decreased, no signficant difference in incidence of cardiovascular system malformation was observed. The mice which were administered estradiol on the 7th day of pregnancy showed a lower incidence of cardiovascular system malformation.