Experimental study on cleft lip and palate

We are maintaining three strains of mice, A/J, CL/Fr, A/Wy with spontaneous cleft lip and palate in an attempt to investigate genetic and fetal environmental influences on the development of teratogenecity. In this paper, we report our findings on the spontaneous incidences of such deformity in A/J strain mice raised in our laboratory. We confirmed vaginal embolus of mother animals used for experiments on the day after mating, designated as the zero pregnant day. As the secondary palate closes around the 15 th embryonic day in A/J strain mice, mother animals were sacrificed by cervical dislocation on the 18 th embryonic day; fetuses were then removed by cesarean section for observation. As a result, the mean fetuses implantation rate was confirmed to be 11.03 out of 51 samples with 7.35 living fetuses on average, of which 8.8% showed cleft lip and/or palate. When classified by cleft type, cleft lip was observed in 0 (0%), cleft lip and palate in 23 (69.7%), and cleft palate 10 (30.3%).