Practice question

Compaction of eight-cell morula into tightly adherent structure critical for blastocyst formation relies on calcium-dependent adhesion complex E-cadherin, beta-catenin, alpha-catenin and actin. Homophilic E-cadherin bonds stabilize blastomere contacts, intracellularly recruiting beta-catenin which anchors to cytoskeleton enabling polarization, increased compaction and sealing. This complex activates downstream Hippo signaling distinctions between inside and outside cells. Actin-myosin contractility participates downstream, but tubulin-kinesin or dynactin complexes are not primary drivers. Genetic ablation of E-cadherin or beta-catenin prevents compaction leading to embryonic lethality, highlighting cadherin-catenin complex as essential architectural organizer of early mammalian morphogenesis and lineage segregation.