Teratogenic induced (AB/Jena) and genetically determined (A/WySn) cleft appearance in special inbred miceis not sex-related. Even the prevention of teratogenic induced clefts, by the application of B1, did not prefer a gender. This positive influence of B1-substitution during pregnancy did not show any benefit to reduce the cleft rate of the genetically determined A/WySn-mouse. In contrast palatal organ cultures of this strain were influenced positively by poly B-vitamins in the media. Therefore a direct effect of the B-vitamins, especially B1, on the developing tissue surface of the face is assumed. Vitamin B1, B5 and B9 in the amniotic fluid of mothers with clefts in their offspring were significantly lower than in mothers without. Indeed B1-substitution could increase the serum level in the A/WySn-mouse, but not the level in the amniotic fluid. Therefore a splice-variant of the ThTr-2 receptor was found to be the reason.