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

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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.