[Characteristics of the stages of the preimplantation period of laboratory mouse embryonic development].

A study was made of the duration of early developmental stages in F1CBA/C57BL mouse hybrid embryos. It was found that the longest were zygota and 2-cell stages. During cleavage the developmental stages became about 2 times shorter. The 4-cell stage was the shortest. The duration of the cleavage stages in the test mouse embryos was different from that in mouse embryos of other strains reported in the literature. These findings suggest that the genetic features of mice belonging to different strains exert an effect on the duration of cleavage stages.