MOLECULAR BIOLOGY OF THE EARLY MOUSE EMBRYO

Abstract

The transition from maternal to embryonic control of development in the early mouse embryo occurs during the 2-cell stage. By the 2-cell stage, all classes of RNA are transcribed from the embryonic genome. Most of the changes in protein synthetic pattern that occur during the first cleavage are post-transcriptionally regulated. Later events, including compaction and blastocyst formation, require transcription from the embryonic genome, but some elements of post-transcriptional regulation are also involved. The result of the preimplantation developmental period is the formation of the blastocyts with two distinct cell types, the trophectoderm and inner cell mass cells. Each cell type is committed to a different developmental pathway and exhibits specific patterns of protein synthesis and DNA methylation.