[Effect of maternal genotype on the rate of preimplantation development in mice]

The genetic control of the rate of preimplantation development was studied in the mouse embryos. The number of cells in the embryo and the percentage of embryos at the blastocyst stage were determined on the 3.5 day of pregnancy. The experiments were carried out with CBA, A/He, C57Bl/Mib mice and mice homozygous by the mutant genes white (Miwh), fidget (fi) and ocular retardation (or), congenic with the inbred C57Bl/Mib mice. Contrasting differences were found between C57Bl/Mib and fi/fi mice. The rate of development of the morphologically normal C57Bl/Mib and fi/fi and F1 embryo was shown to depend on the maternal genotype, rather than on the paternal one. The effect of maternal genotype of the rate of preimplantation development was related to differences in the time of beginning of the cleavage. The rate of cleavage is similar for the C57Bl/Mib, fi/fi and F1 embryos.