II. Intrauterine effect of dam on prenatal development of craniofacial complex of mouse embryo

Embryo transfer effect and intrauterine effect of the dam on prenatal development of the craniofacial complex of mice embryos were investigated with the use of embryo transfer and cephalostat. DDD strain embryos were transferred to the three strains of recipients (DDD, C57BL, and DBA). The cephalometric observation of newborn offspring developed from transferred embryos was performed just after parturition. Dorso-ventral craniofacial size of newborn offspring was calculated using values of X- and Y- coordinates on a dorsoventral cephalogram. Statistical analysis showed that a significant intergroup difference in craniofacial size between transferred and nontransferred groups as well as a significant inter-strain difference among those of the three strains of recipients were observed. Thus, it was disclosed that embryo transfer technique might retard the prenatal development of craniofacial complex of transferred embryo and that the three strains of recipients contributed unequally to the prenatal development of craniofacial complex of transferred embryo through each of their intrauterine environments as a prenatal maternal effect. These results indicated that the intrauterine environment of the recipient played an important role in the prenatal development of the craniofacial complex of the mice embryo.