[Regulation of compaction initiation in mouse embryo].

Area of Science:

• Developmental Biology
• Cell Biology
• Genomics

Context:

• Preimplantation mouse embryos undergo critical developmental milestones including first cleavage, embryonic genome activation, morula (MO) formation, and blastocyst (BL) development.
• Compaction, occurring at the late eight-cell stage, is the first cell differentiation event in mammalian development, involving significant cellular and intercellular reorganization.
• This process is essential for establishing distinct cell lineages, namely the inner cell mass (embryo proper) and trophectoderm (extraembryonic tissues).

Purpose:

• To detail the morphological and molecular mechanisms underlying compaction in preimplantation mouse embryos.
• To elucidate the role of E-cadherin-mediated cell adhesion in initiating and regulating compaction.
• To review the influence of compaction on subsequent blastocyst formation and lineage specification.

Summary:

• Compaction involves blastomere flattening, restricted microvilli localization to apical/basal poles, and loss of spherical morphology, maximizing intercellular contact.
• E-cadherin-mediated homophilic interactions initiate compaction, with regulation by protein kinase C; maternal E-cadherin can rescue compaction in knock-out models.
• Successful compaction is a prerequisite for initiating inner cell mass and trophectoderm differentiation, guiding the formation of the blastocyst.

Impact:

• Provides a comprehensive understanding of a fundamental process in early mammalian development.
• Highlights the critical role of cell adhesion molecules like E-cadherin in tissue morphogenesis and differentiation.
• Offers insights into potential mechanisms underlying developmental abnormalities related to compaction.