THE EFFECT OF 4 STRAINS OF RECIPIENTS ON THE INTRAUTERINE GROWTH OF THE MANDIBLE IN MOUSE FETUSES

The embryo transfer technique is a very useful tool for determining the intrauterine effect of the dam on the prenatal growth of the embryo. In the present study, a DDD/Qdj strain of embryos was transferred to four strains of recipients (DDD/Qdj, C3H/Qdj, C57BL/Qdj, and DBA/1J Sea). The litter size and the gestation period were recorded and the mandibular size of the newborn offspring was measured by an image analyzing system. A comparison among the four strains of recipients was performed to examine the effect of the strain of the recipient on the intrauterine growth of the mandible in mouse fetuses. The following results were obtained. 1) There were no interstrain differences in the litter size and the gestation period among the four strains of recipients. 2) There was an inverse relation between the litter size and the mandibular size, while there was a direct relation between the gestation period and the mandibular size. 3) There was a strong effect of the strain of the recipient on the mandibular size of the newborn offspring. 4) After eliminating these effects of the litter size and the gestation period on the mandibular size, a significant interstrain difference in the adjusted mandibular size of the newborn offspring developed from the DDD/Qdj strain of embryos transferred to the four strains of recipients was found. It is suggested that the four strains of recipients might unequally affect the intrauterine growth of the mandible in the mouse fetuses, which were derived from the same DDD/Qdj strain of transferred embryos. Thus, it is concluded that the uterine environment of the recipient played an important role in the intrauterine growth of the mandible in mouse fetuses.