Abstract
The necessity of cell contact during the third cell cycle for the formation of compacted mouse embryos at the 8-cell stage was examined. Early 4-cell embryos (0-2 h post division) were disaggregated into 4 blastomeres, and then reaggregated at the early, mid or late stage of the third cell cycle. The reaggregated embryos were cultured upto the 16-cell stage, and the features of compaction were observed. Embryos reaggregated at the mid or late stage of the third cell cycle, had their compaction retarded by 2 h as compared with control embryos. In embryos reaggregated at the mid or late stage, the establishment of gap junctional communication was also retarded. We concluded that cell contact from the early to the mid stage of the third cell cycle is necessary to regulate the events during compaction, especially for the establishment of the gap junction.
