Influence of embryonic and maternal genotype on gestational events in the mouse

Mice with high and low prenatal survival were used to study the influence of maternal and embryonic genotype on the timing of implantation, conceptus growth and gestation length. Mice selected for large litter size (Line S1) or rapid post-weaning weight gain (Line G) showed implantation was delayed and gestation prolonged in mice with low prenatal survival (Line G). Reciprocal transfer of Line-S1 and -G embryos to pseudopregnant recipients indicated that conceptus growth was influenced by maternal as well as embryonic genes, at least until mid-pregnancy. In contrast, fetal genotype had a major effect on the length of gestation.