Mammalian Embryo Culture from the Pre‐Implantation Stage, and Analysis of Developmental Failures due to Chromosomal Abnormalities in Vitro*

Abstract

Abstract In vitro culture methods make it possible to manipulate mammalian embryos experimentally, and continuous observation of the developmental processes furnishes significant information for mammalian embryology. The advancement in the culture methods of the mouse embryos from the pre‐implantation through the limb bud stage is reported here, along with a description of one of the applied experiments of embryo culture from the pre‐implantation stage in the Chinese hamster.A few mouse embryos at the limb bud stage cultured for 10 or 11 days from the blastocyst stage were obtained, but the frequencies were very low. There is a barrier to assure further development in the stationary culture of mouse blastocysts till the formation of early egg cylinder. It was suggested that trophectoderm inhibited the development of inner cell masses by enveloping them, but embryos could not develop without trophectoderm afterwards. After the egg cylinder or primitive streak stage, the medium and gas around the embryos needed to be exchanged with rotation or shaking.Chinese hamster blastocysts could be cultured as late as the early egg cylinder stage with methods similar those employed with mouse blastocysts. Sonta (1982) has established several lines of Chinese hamster bearing various reciprocal translocations. Thus, one can obtain embryos with abnormal karyotypes from these parents. By cultivation of these embryos from the pre‐implantation stage, the present authors investigated the relationship between the developmental failures and the chromosomal abnormalities.